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Dell Pro Slim QCS1255 Owner's Manual

Dell Pro Slim QCS1255 Owner's Manual

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Dell Pro Slim
QCS1255
Owner's Manual
Regulatory Model: D18S
Regulatory Type: D18S004
March 2025
Rev. A00

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Summary of Contents for Dell Pro Slim QCS1255

  • Page 1 Dell Pro Slim QCS1255 Owner's Manual Regulatory Model: D18S Regulatory Type: D18S004 March 2025 Rev. A00...
  • Page 2 A WARNING indicates a potential for property damage, personal injury, or death. © 2025 Dell Inc. or its subsidiaries. All rights reserved. Dell Technologies, Dell, and other trademarks are trademarks of Dell Inc. or its subsidiaries. Other trademarks may be trademarks of their respective owners.

  • Page 3: Table Of Contents

    Contents Chapter 1: Views of Dell Pro Slim QCS1255..................7 Front....................................... 7 Back......................................8 Top......................................10 Chapter 2: Set up your computer....................11 Chapter 3: Specifications of Dell Pro Slim QCS1255..............15 Dimensions and weight..............................15 Processor..................................... 15 Chipset....................................16 Operating system................................16 Memory....................................16 External ports and slots..............................
  • Page 4 Chapter 6: Side cover........................32 Removing the side cover..............................32 Installing the side cover..............................33 Chapter 7: Coin-cell battery cover....................36 Removing the coin-cell battery cover.......................... 36 Installing the coin-cell battery cover..........................36 Chapter 8: Coin-cell battery......................38 Removing the coin-cell battery............................38 Installing the coin-cell battery............................39 Chapter 9: Removing and installing Customer Replaceable Units (CRUs)........
  • Page 5 Installing the Intrusion switch...........................67 Power button..................................68 Removing the power button.............................68 Installing the power button............................69 Chapter 10: Removing and installing Field Replaceable Units (FRUs)........... 71 Antenna modules................................71 Removing the antenna modules..........................71 Installing the antenna modules..........................72 Power-supply unit................................74 Removing the power-supply unit..........................
  • Page 6 Chapter 13: Troubleshooting.......................117 Dell SupportAssist Pre-boot System Performance Check diagnostics............... 117 Running the SupportAssist Pre-Boot System Performance Check............... 117 Power-Supply Unit Built-in Self-Test ......................... 117 System-diagnostic lights..............................117 Recovering the operating system..........................118 Real-Time Clock—RTC reset............................118 Backup media and recovery options..........................119 Network power cycle..............................

  • Page 7: Chapter 1: Views Of Dell Pro Slim Qcs1255

    Views of Dell Pro Slim QCS1255 Front Figure 1. Front view of Dell Pro Slim QCS1255 1. Power button with diagnostic LED Press to turn on the computer if it is turned off, in sleep state, or in hibernate state.

  • Page 8: Back

    Reads from and writes to CDs and DVDs. Back Figure 2. Back view of Dell Pro Slim QCS1255 1. DisplayPort 1.4a (HBR3) port Connect an external display or a projector. The maximum resolution that is supported by this port is up to 5120 x 3200 at 60 Hz (HBR3).
  • Page 9 ● Two USB 3.2 Gen 2 (10 Gbps) ports Connect devices such as external storage devices and printers. Provides a data transfer speed of up to 10 Gbps. 13. Serial port (optional) Connect serial I/O devices. 14. Service Tag label Views of Dell Pro Slim QCS1255...

  • Page 10: Top

    Figure 3. Top view of Dell Pro Slim QCS1255 1. MyDell QR code MyDell is your hub for content that is personalized to your Dell Pro Slim QCS1255, including videos, articles, manuals, and easy access to support. Views of Dell Pro Slim QCS1255...

  • Page 11: Chapter 2: Set Up Your Computer

    Set up your computer Steps 1. Connect the keyboard and mouse. 2. Connect to your network using a cable, or connect to a wireless network. Set up your computer...
  • Page 12 3. Connect the display. 4. Connect the power cable. Set up your computer...
  • Page 13 Follow the on-screen instructions to complete the setup. For more information about installing and configuring Ubuntu, search in the Knowledge Base Resource at Dell Support Site. For Windows: Follow the on-screen instructions to complete the setup. When setting up, Dell Technologies recommends that you: Set up your computer...
  • Page 14 Table 1. Locate Dell apps  Resources Description Dell Optimizer is an application designed to enhance computer performance and productivity by optimizing settings for power, battery, display, collaboration touchpad, and presence detection. It also provides access to applications purchased with your new computer.

  • Page 15: Chapter 3: Specifications Of Dell Pro Slim Qcs1255

    The weight of your computer depends on the ● Maximum: 5.68 kg (12.52 lb) configuration that is ordered. Processor The following table lists the details of the processors that are supported in your Dell Pro Slim QCS1255. Table 3. Processor  Description Option 1...

  • Page 16: Chipset

    Tera Operations Per Second (TOPS) is an AI performance metric that measures how many trillions of operations per second an AI processor can perform. Chipset The following table lists the details of the chipset that is supported by your Dell Pro Slim QCS1255. Table 4. Chipset  Description...

  • Page 17: External Ports And Slots

    The following table lists the external ports that are supported on the optional module slot for Dell Pro Slim QCS1255. NOTE: The ports that are listed in this table are mutually exclusive. Your Dell Pro Slim QCS1255 can only support one of the listed options.

  • Page 18: Internal Slots

    Model Realtek RTL8111EPP Transfer rate 10/100/1000 Mbps Wireless module The following table lists the Wireless Local Area Network (WLAN) modules that are supported on your Dell Pro Slim QCS1255. Table 10. Wireless module specifications  Description Option one Option two Model number...

  • Page 19: Audio

    Your Dell Pro Slim QCS1255 supports a combination of the following storage configurations: ● One 3.5-inch hard-drive ● One M.2 2230/2280 solid state drive The primary drive of your Dell Pro Slim QCS1255 is the M.2 solid state drive. Table 12. Storage specifications  Storage type...

  • Page 20: Power Supply Connector

    ● One 8-pin connector for the system board ● One 8-pin header for the graphic card GPU—Integrated The following table lists the specifications of the integrated Graphics Processing Unit (GPU) supported by your Dell Pro Slim QCS1255. Table 15. GPU—Integrated ...

  • Page 21: Hardware Security

    Hardware security The following table lists the hardware security of your Dell Pro Slim QCS1255. Table 16. Hardware security   Hardware security Chassis intrusion switch Chassis lock slot support Security-cable slot (Kensington lock) Local hard drive data wipe through BIOS (Secure Erase)

  • Page 22: Regulatory Compliance

    Dell Regulatory Compliance Home Page Responsible Business Alliance policy Operating and storage environment This table lists the operating and storage specifications of your Dell Pro Slim QCS1255. Airborne contaminant level: G1 as defined by ISA-S71.04-1985 Table 19. Computer environment  Description...

  • Page 23: Chapter 4: Working Inside Your Computer

    You should only perform troubleshooting and repairs as authorized or directed by the Dell technical support team. Damage due to servicing that is not authorized by Dell is not covered by your warranty. See the safety instructions that are shipped with the product or at Dell Regulatory Compliance Home Page.

  • Page 24: Safety Precautions

    Standby power Dell products with standby power must be unplugged before you open the back cover. Systems that are equipped with standby power are powered while turned off. The internal power enables the computer to be remotely turned on (Wake-on-LAN) and suspended into a sleep mode and has other advanced power management features.

  • Page 25: Esd Field Service Kit

    NOTE: It is recommended to always use the traditional wired ESD grounding wrist strap and protective anti-static mat when servicing Dell products. In addition, it is critical to keep sensitive parts separate from all insulator parts while servicing the computer.

  • Page 26: Transporting Sensitive Components

    Transporting sensitive components When transporting ESD sensitive components such as replacement parts or parts to be returned to Dell, it is critical to place these parts in anti-static bags for safe transport. Lifting equipment Adhere to the following guidelines when lifting heavy equipment: CAUTION: Do not lift greater than 50 pounds.

  • Page 27: Screw List

    Screw list NOTE: When removing screws from a component, it is recommended to note the screw type and the quantity of screws, and then place them in a screw storage box. This is to ensure that the correct number of screws and correct screw type is restored when the component is replaced.

  • Page 28: Major Components Of Dell Pro Slim Qcs1255

    Major components of Dell Pro Slim QCS1255 The following image shows the major components of Dell Pro Slim QCS1255. 1. Side cover 2. Graphics card 3. Processor 4. Memory module 5. M.2 2280 solid state drive 6. System board 7. Chassis 8.
  • Page 29 19. Intrusion switch NOTE: Dell provides a list of components and their part numbers for the original system configuration purchased. These parts are available according to warranty coverages purchased by the customer. Contact your Dell sales representative for purchase options.

  • Page 30: Chapter 5: Cable Cover

    Cable cover Removing the cable cover Prerequisites 1. Follow the procedure in Before working inside your computer. About this task The following image indicates the location of the cable cover and provides a visual representation of the removal procedure. Figure 4. Removing the cable cover Steps 1.
  • Page 31 Figure 5. Installing the cable cover Steps 1. Align the tabs on the cable cover to the slots on the back of the chassis. 2. Insert the tabs on the cable cover into the slots on the back of the chassis and slide downwards. 3.

  • Page 32: Chapter 6: Side Cover

    Side cover Removing the side cover Prerequisites 1. Follow the procedure in Before working inside your computer. 2. Remove the cable cover, if applicable. About this task The following images indicate the location of the side cover and provide a visual representation of the removal procedure. Figure 6.

  • Page 33: Installing The Side Cover

    Figure 7. Removing the side cover Steps 1. Place the computer on its side with the side cover facing up. 2. Loosen the two captive screws (6-32#) that secure the side cover to the chassis. 3. Slide the side cover towards the back of the computer. 4.
  • Page 34 Figure 8. Installing the side cover Figure 9. Installing the side cover Side cover...
  • Page 35 Steps 1. Align the tabs on the side cover with the slots on the chassis. 2. Slide the side cover towards the front of the computer. 3. Tighten the two captive screws (6-32#) that secure the side cover to the chassis. 4.

  • Page 36: Chapter 7: Coin-Cell Battery Cover

    Coin-cell battery cover Removing the coin-cell battery cover Prerequisites 1. Follow the procedure in Before working inside your computer. 2. Remove the cable cover, if applicable. 3. Remove the dust filter, if applicable. 4. Remove the side cover. 5. Remove the front cover.
  • Page 37 About this task The following image indicates the location of the coin-cell battery cover and provides a visual representation of the installation procedure. Figure 11. Installing the coin-cell battery cover Steps Align the coin-cell battery cover with the battery socket (RTC) and press it into place. Next steps 1.

  • Page 38: Chapter 8: Coin-Cell Battery

    Coin-cell battery Removing the coin-cell battery WARNING: This computer contains a coin-cell battery and requires trained technicians for handling guidance. CAUTION: Removing the coin-cell battery will clear the CMOS and will reset BIOS settings. Prerequisites 1. Follow the procedure in Before working inside your computer.

  • Page 39: Installing The Coin-Cell Battery

    Installing the coin-cell battery WARNING: This computer contains a coin-cell battery and requires trained technicians for handling guidance. Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure. About this task The following images indicate the location of the coin-cell battery and provide a visual representation of the installation procedure.

  • Page 40: Chapter 9: Removing And Installing Customer Replaceable Units (Crus)

    Removing and installing Customer Replaceable Units (CRUs) The replaceable components in this chapter are Customer Replaceable Units (CRUs). CAUTION: Customers can replace only the Customer Replaceable Units (CRUs) following the safety precautions and replacement procedures. NOTE: The images in this document may differ from your computer depending on the configuration you ordered. Dust filter Removing the dust filter Prerequisites...

  • Page 41: Installing The Dust Filter

    Installing the dust filter Prerequisites If you are replacing a component, remove the existing component before performing the installation process. About this task The following image indicates the location of the dust filter and provides a visual representation of the installation procedure. Figure 15.

  • Page 42: Installing The Front Cover

    Figure 16. Removing the front cover Steps 1. Gently pry and release the front-cover tabs one by one. 2. Pivot the front cover outward from the chassis and remove the front cover. Installing the front cover Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure. About this task The following images indicate the location of the front cover and provide a visual representation of the installation procedure.

  • Page 43: Internal Speaker

    Figure 17. Installing the front cover Steps 1. Insert the shorter front-cover tabs into the corresponding slots on the chassis. 2. Pivot the front cover on the shorter front-cover tabs toward the chassis, snapping the longer front-cover tabs into place. Next steps 1.

  • Page 44: Installing The Internal Speaker

    Figure 18. Removing the internal speaker Steps 1. Disconnect the internal-speaker cable from its connector (INT SPKR) on the system board. 2. Remove the internal-speaker cable from the routing guide on the chassis. 3. Slide and remove the internal speaker from the chassis. Installing the internal speaker Prerequisites If you are replacing a component, remove the existing component before performing the installation process.

  • Page 45: Memory

    Figure 19. Installing the internal speaker Steps 1. Place and slide the internal speaker into the bracket on the chassis. 2. Route the internal-speaker cable through the routing guide on the chassis. 3. Connect the internal-speaker cable to its connector (INT SPKR) on the system board. Next steps 1.

  • Page 46: Installing The Memory Module

    About this task The following images indicate the location of the memory modules and provide a visual representation of the removal procedure. Figure 20. Removing a memory module Steps 1. Use your fingertips to carefully spread apart the securing clips on each end of the memory-module slot (DIMM1 or DIMM2, whichever is applicable) .

  • Page 47: Solid State Drive

    Figure 21. Installing the memory module Steps 1. Ensure that the memory-module securing clips are in an open position. 2. Align the notch on the memory module with the tab on the memory-module slot (DIMM1 or DIMM2, whichever is applicable). 3.

  • Page 48: Installing The M.2 2230 Solid State Drive

    5. Remove the front cover. 6. Remove the drive bay. About this task NOTE: This procedure only applies if there is an M.2 2230 solid state drive that is installed in M.2 solid state drive slot 0 (M.2 PCIe SSD - 0) NOTE: Ensure that the mounting screw is in the correct location to install the M.2 2230 solid state drive, see Location of...

  • Page 49: Removing The M.2 2280 Solid State Drive

    Figure 23. Installing the M.2 2230 solid state drive Steps 1. Align the notch on the solid state drive with the tab on the M.2 solid state drive slot (M.2 PCIe SSD - 0). 2. Slide the solid state drive into the slot on the system board. 3.

  • Page 50: Installing The M.2 2280 Solid State Drive

    Figure 24. Removing the M.2 2280 solid state drive Steps 1. Remove the screw (M2x3) that secures the solid state drive to the system board. 2. Slide and lift the solid state drive from the M.2 solid state drive slot (M.2 PCIe SSD - 0) on the system board. Installing the M.2 2280 solid state drive Prerequisites If you are replacing a component, remove the existing component before performing the installation process.

  • Page 51: Location Of The Screw Mount On M.2 Slot 0

    Figure 25. Installing the M.2 2280 solid state drive Steps 1. Align the notch on the solid state drive with the tab on the M.2 solid state drive slot (M.2 PCIe SSD - 0). 2. Slide the solid state drive into the slot on the system board. 3.

  • Page 52: Graphics Card

    Figure 26. Moving the mounting screw to the screw mount for M.2 2280 solid state drive Steps 1. Remove the mounting screw from the system board. 2. Install the mounting screw on the screw mount for the appropriate form factor on the system board. Next steps 1.

  • Page 53: Installing The Graphics Card

    Figure 27. Removing the graphics card Steps 1. Open the PCIe latch that secures the graphics card to the PCI card connector (SLOT 3). 2. Push the tab that secures the graphics card to the PCIe card connector (SLOT 3). 3.

  • Page 54: Wireless Card

    Figure 28. Installing the graphics card Steps NOTE: Ensure that the PCIe door is in the open position and the release tab on the PCIe card connector (SLOT 2) is up. Align the graphics card with the PCIe card connector (SLOT 3) on the system board. 2.

  • Page 55: Installing The Wireless Card

    Figure 29. Removing the wireless card Steps 1. Remove the screw (M2x3.5) that secures the wireless-card bracket to the system board. 2. Slide and lift the wireless-card bracket off the wireless card. 3. Disconnect the antenna cables from the wireless card. 4.
  • Page 56 Figure 30. Installing the wireless card Steps 1. Connect the antenna cables to the wireless card. Table 21. Antenna-cable color scheme  Connector on the Antenna-cable color Silkscreen marking wireless card △ (white triangle) Main White MAIN Auxiliary Black ▲ (black triangle) 2.

  • Page 57: Optical Drive

    Optical drive Removing the optical drive Prerequisites 1. Follow the procedure in Before working inside your computer. 2. Remove the cable cover, if applicable. 3. Remove the dust filter, if applicable. 4. Remove the side cover. 5. Remove the front cover.

  • Page 58: Installing The Optical Drive

    Figure 32. Removing the optical drive Steps 1. Disconnect the data cable and the power cable from the optical drive. 2. Press down on the securing tab to release the optical drive from the drive bay. 3. Pull to slide the optical drive out of the drive bay. 4.
  • Page 59 Figure 33. Installing the optical drive Removing and installing Customer Replaceable Units (CRUs)

  • Page 60: Drive Bay

    Figure 34. Installing the optical drive Steps 1. Align the tabs on the bezel with the slots on the optical drive. 2. Press the bezel against the optical drive until the bezel clicks into place. 3. Insert the alignment post on the securing tab into the hole on the optical drive. 4.
  • Page 61 4. Remove the side cover. 5. Remove the front cover. About this task The following images indicate the location of the drive bay and provide a visual representation of the removal procedure. Figure 35. Removing the drive bay Removing and installing Customer Replaceable Units (CRUs)

  • Page 62: Installing The Drive Bay

    Figure 36. Removing the drive bay Steps 1. Disconnect the data cable and the power cable from the optical drive. 2. Remove the data cable and the power cable from the routing guide on the drive bay. 3. Disconnect the data cable and the power cable from the hard drive. 4.
  • Page 63 Figure 37. Installing the drive bay Figure 38. Installing the drive bay Steps 1. While holding the drive bay firmly with both hands, slide and secure one side of the drive bay to the chassis. Removing and installing Customer Replaceable Units (CRUs)

  • Page 64: Hard Drive

    2. Press down the other end of the drive bay securing the tabs on the drive bay with the slots on the chassis. 3. Connect the data cable and the power cable to the hard drive. 4. Connect the data cable and the power cable to the optical drive. 5.

  • Page 65: Installing The Hard Drive

    Figure 39. Removing the hard drive Steps 1. Flip the drive bay over to reveal the hard drive. 2. While pulling the securing tab away from the side of the hard drive, slide and lift the hard disk at an angle off the drive bay. 3.
  • Page 66 Figure 40. Installing the hard drive Steps 1. Replace the four screws (6-32#) on the hard drive. 2. Align the screws on the hard drive with the grooves on the drive bay and slide the hard drive until it clicks into place. 3.

  • Page 67: Intrusion Switch

    Intrusion switch Removing the intrusion switch CAUTION: The information in this removal section is intended for authorized service technicians only. Prerequisites 1. Follow the procedure in Before working inside your computer. 2. Remove the cable cover, if applicable. 3. Remove the dust filter, if applicable.

  • Page 68: Power Button

    About this task The following image indicates the location of the Intrusion switch and provides a visual representation of the installation procedure. Figure 42. Installing the Intrusion switch Steps 1. Slide the intrusion switch into the slot on the chassis. 2.

  • Page 69: Installing The Power Button

    About this task The following image indicates the location of the power button and provides a visual representation of the removal procedure. Figure 43. Removing the power button Steps 1. Remove the processor power cables from the routing guide on the chassis. 2.
  • Page 70 Figure 44. Installing the power button Steps 1. Thread the power-button module cable through the slot on the front of the chassis. 2. Align the tabs on the side of the power button with the cutouts on the slot in the chassis. 3.

  • Page 71: Chapter 10: Removing And Installing Field Replaceable Units (Frus)

    The information in this removing and installing FRUs section is intended for authorized service technicians only. CAUTION: To avoid any potential damage to the component or loss of data, Dell Technologies recommends that an authorized service technician replaces the Field Replaceable Units (FRUs). CAUTION: Your warranty does not cover damages that may occur during FRU repairs that are not authorized by Dell Technologies.

  • Page 72: Installing The Antenna Modules

    Figure 45. Removing the antenna modules Steps 1. Gently remove the antenna cable from the routing guide on the chassis interior. 2. Remove the screw (6-32#) that secures the antenna modules to the chassis. 3. Thread the antenna cables through the slot on the chassis. 4.
  • Page 73 Figure 46. Installing the antenna modules Steps 1. Thread the antenna cables through the slot on the chassis. 2. Place the antenna modules on the chassis. 3. Align the screw hole on the antenna modules with the screw hole on the chassis. 4.

  • Page 74: Power-Supply Unit

    Power-supply unit Removing the power-supply unit CAUTION: The information in this section is intended for authorized service technicians only. Prerequisites 1. Follow the procedure in Before working inside your computer. 2. Remove the cable cover, if applicable. 3. Remove the dust filter, if applicable.
  • Page 75 Figure 47. Removing the power-supply unit Removing and installing Field Replaceable Units (FRUs)

  • Page 76: Installing The Power-Supply Unit

    Figure 48. Removing the power-supply unit Steps 1. Disconnect the power-supply cables from their connectors (ATX CPU1 and ATX SYS) on the system board. 2. Remove the power-supply cables from the routing guides on the chassis. 3. Remove the three screws (6-32#) that secure the power-supply unit to the chassis. 4.
  • Page 77 Figure 49. Installing the power-supply unit Removing and installing Field Replaceable Units (FRUs)

  • Page 78: Processor Fan And Heat-Sink Assembly

    Figure 50. Installing the power-supply unit Steps 1. Place the power-supply unit on the chassis and slide it towards the back of the chassis. 2. Replace the three screws (6-32#) that secure the power-supply unit to the chassis. 3. Route the power-supply cables through their routing guides on the chassis. 4.

  • Page 79: Installing The Processor Fan And Heat-Sink Assembly

    Prerequisites 1. Follow the procedure in Before working inside your computer. 2. Remove the cable cover, if applicable. 3. Remove the dust filter, if applicable. 4. Remove the side cover. 5. Remove the front cover. 6. Remove the drive bay. About this task The following images indicate the location of the processor fan and heat-sink assembly and provide a visual representation of the removal procedure.

  • Page 80: External Port (Optional Module)

    About this task The following image indicates the location of the processor fan and heat-sink assembly and provides a visual representation of the installation procedure. NOTE: If either the processor fan and heat-sink assembly is replaced, use the thermal grease provided in the kit for thermal conductivity.

  • Page 81: Installing The Optional-Port Module

    Prerequisites 1. Follow the procedure in Before working inside your computer. 2. Remove the cable cover, if applicable. 3. Remove the dust filter, if applicable. 4. Remove the side cover. 5. Remove the front cover. 6. Remove the drive bay. 7.
  • Page 82 About this task NOTE: The optional-port modules are mutually exclusive; only a single module can be installed at a time. The following images indicate the location of the optional-port module and provide a visual representation of the installation procedure. Figure 54. Installing the optional-port module Removing and installing Field Replaceable Units (FRUs)
  • Page 83 Figure 55. Installing the optional-port module Steps 1. Using a screwdriver, push against the optional-port cover until it comes off. NOTE: This step is only applicable if you are installing the optional-port module on a computer that did not previously have it installed.

  • Page 84: Serial-Port Module

    Serial-port module Removing the serial-port module CAUTION: The information in this section is intended for authorized service technicians only. Prerequisites 1. Follow the procedure in Before working inside your computer. 2. Remove the cable cover, if applicable. 3. Remove the dust filter, if applicable.

  • Page 85: Installing The Serial-Port Module

    Figure 56. Removing the serial-port module Steps 1. Remove the two screws (M3) that secure the optional serial-port module to the chassis. 2. Disconnect the serial-port module cable from the connector (KB MS SERIAL) on the system board. 3. Push the serial port through its slot on the chassis and lift the serial-port module off the system board. Installing the serial-port module CAUTION: The information in this section is intended for authorized service technicians only.
  • Page 86 Figure 57. Installing the serial-port module Removing and installing Field Replaceable Units (FRUs)

  • Page 87: Processor

    Figure 58. Installing the serial-port module Steps 1. Using a screwdriver, push against the serial-port cover until it comes off. NOTE: This step is only applicable if the serial-port module is not previously installed on the computer. 2. Insert the serial-port module into its slot on the chassis. 3.

  • Page 88: Installing The Processor

    Prerequisites 1. Follow the procedure in Before working inside your computer. 2. Remove the cable cover, if applicable. 3. Remove the dust filter, if applicable. 4. Remove the side cover. 5. Remove the front cover. 6. Remove the drive bay. 7.

  • Page 89: System Board

    Figure 60. Installing the processor Steps 1. Ensure that the release lever on the processor socket is fully extended in the open position. NOTE: The pin-1 corner of the processor has a triangle that aligns with the triangle on the pin-1 corner on the processor socket.
  • Page 90 4. Remove the side cover. 5. Remove the coin-cell battery cover. 6. Remove the coin-cell battery. 7. Remove the front cover. 8. Remove the memory. 9. Remove the M.2 2230 solid state drive, or the M.2 2280 solid state drive, whichever is applicable. 10.
  • Page 91 10. Hard-drive data connector (SATA - 0) 11. Optical-drive data connector (SATA - 3) 12. Coin-cell battery socket (RTC) 13. Solid state drive slot (M.2 PCIe SSD - 0) 14. Wireless-card slot (M.2 WLAN) 15. PCIe x16 slot (SLOT 3) 16.
  • Page 92 Figure 63. Removing the system board 3. Disconnect the power-supply cable from its connector (ATX CPU1) on the system board. 4. Remove the power-supply cable from the routing guides and keep it away. 5. Disconnect the power-button cable from its connector (PWR SW) on the system board. 6.
  • Page 93 Figure 64. Removing the system board 12. Remove the six screws (6-32#)) that secure the system board to the chassis. 13. Remove the screw mount that secures the system board to the chassis. Removing and installing Field Replaceable Units (FRUs)

  • Page 94: Installing The System Board

    Figure 65. Removing the system board 14. Free the system board from the back I/O panel by sliding it towards the right and lift the system board out of the chassis. Installing the system board CAUTION: The information in this removal section is intended for authorized service technicians only. Prerequisites If you are replacing a component, remove the existing component before performing the installation procedure.
  • Page 95 Figure 66. System board overview 1. Intrusion-switch connector (INTRUSION) 2. Processor-power connector (ATX CPU1) 3. Processor socket (CPU) 4. Processor-fan and heat-sink assembly connector (FAN CPU) 5. UDIMM memory slot (DIMM1) 6. UDIMM memory slot (DIMM2) 7. Power-button connector (PWR SW) 8.
  • Page 96 Figure 67. Installing the system board Steps 1. Align and lower the system board into the system until the stand-off points at the back of the system board align with those on the chassis. Removing and installing Field Replaceable Units (FRUs)
  • Page 97 Figure 68. Installing the system board 2. Replace the screw mount that secures the system board to the chassis. 3. Replace the six (6-32#)) screws that secure the system board to the chassis. Removing and installing Field Replaceable Units (FRUs)
  • Page 98 Figure 69. Installing the system board 4. Route and connect the power-supply cable to its connector (ATX CPU1) on the system board. 5. Route and connect the power-button cable to its connector (PWR SW) on the system board. 6. Route and connect the power-supply cable to its connector (ATX SYS) on the system board. 7.
  • Page 99 13. Replace the screw (6-32#) that secures the front I/O-bracket to the chassis. Next steps 1. Install the processor. 2. Install the optional-port module, if applicable. 3. Install the serial-port module, if applicable. 4. Install the processor fan and heat-sink assembly.

  • Page 100: Chapter 11: Software

    ● Windows 11 Pro ● Windows 11 Pro National Education ● Ubuntu Linux 24.04 LTS Drivers and downloads When troubleshooting, downloading, or installing drivers, it is recommended that you read the Dell Knowledge Base article Drivers and Downloads FAQs 000123347. Software...

  • Page 101: Chapter 12: Bios Setup

    BIOS Setup NOTE: Depending on the computer and the installed devices, the options that are listed in this section may or may not be displayed. CAUTION: Certain changes can make your computer work incorrectly. Before you change the settings in BIOS Setup, it is recommended that you note down the original settings for future reference.

  • Page 102: F12 One Time Boot Menu

    Depending on your computer and its installed devices, the items that are listed in this section may or may not be displayed. Table 23. BIOS Setup options—Overview menu  Overview Dell Pro Slim QCS1255 BIOS Version Displays the BIOS version number. Service Tag Displays the Service Tag of the computer.
  • Page 103 Table 23. BIOS Setup options—Overview menu (continued) Overview Processor ID Displays the processor identification code. Processor L2 Cache Displays the processor L2 cache size. Processor L3 Cache Displays the processor L3 cache size. Microcode Version Displays the microcode version. Memory Information Memory Installed Displays the total memory that is installed on the computer.
  • Page 104 The computer stops booting to the operating system when a component is not authenticated during the boot process. Secure Boot can be enabled in BIOS setup or using management interfaces like Dell Command|Configure, but can only be disabled from BIOS setup.
  • Page 105 Table 25. BIOS Setup options—Integrated Devices menu (continued) Integrated Devices By default, the Enable Rear External USB Ports option is enabled. Enable USB Boot Support Enables booting from USB mass storage devices that are connected to external USB ports. By default, the Enable USB Boot Support option is enabled. Enable Thunderbolt Technology Support Enables the Thunderbolt adapter devices during pre-boot.
  • Page 106 Table 27. BIOS Setup options—Display menu  Display Primary Display Determines which video controller will become the primary display when there are multiple controllers available. When a specific device is selected display output is only available from ports located on that selected device. Table 28.
  • Page 107 BIOS. This option returns to the disabled state when the computer restarts. By default, the Clear option is disabled. Dell Technologies recommends enabling the Clear option only when TPM data is required to be cleared. PPI Bypass for Clear Commands By default, the PPI Bypass for Clear Commands option is disabled.
  • Page 108 By default, the Start Data Wipe option is disabled. Absolute Absolute Software provides various cyber security solutions, some requiring software preloaded on Dell computers and integrated into the BIOS. To use these features, you must enable the Absolute BIOS setting and contact Absolute for configuration and activation.
  • Page 109 BIOS passwords. You can modify the minimum and maximum length of the passwords and require passwords to contain certain character classes (upper case, lower case, digit, special character). Dell Technologies recommends setting the minimum password length to at least eight characters. Password Bypass The Password Bypass option allows the computer to reboot from the operating system without entering the computer or hard drive password.
  • Page 110 The Recovery Password can be used when a system owner forgets the administrator, system, or hard drive password. You can get an unlock code from Dell Support over the phone after verifying ownership details. The unlock code overrides and removes the existing password.
  • Page 111 Allows you to control the automatic boot flow for SupportAssist System Resolution Console and for Dell OS Recovery Tool. By default, the Dell Auto OS Recovery Threshold value is set to 2. Table 33. BIOS Setup options—System Management menu  System Management Service Tag Displays the Service Tag of the computer.
  • Page 112 This option is not available when the virtualization setting for IOMMU is disabled (VT-d/AMD Vi). By default, the Enable Pre-Boot DMA Support option is enabled. For additional security, Dell Technologies recommends keeping the Enable Pre- Boot DMA Support option enabled. NOTE: This option is provided only for compatibility purposes, since some older hardware is not DMA capable.

  • Page 113: Updating The Bios

    Failure to provide the recovery key can result in data loss or an operating system reinstall. For more information, see the Knowledge Base Resource updating the BIOS on Dell systems with BitLocker enabled. Steps 1.

  • Page 114: Updating The Bios From The One-Time Boot Menu

    ● USB drive formatted to the FAT32 file system (the drive does not have to be bootable) ● BIOS executable file that you downloaded from the Dell Support website and copied to the root of the USB drive ● AC power adapter must be connected to the computer ●...

  • Page 115: Assigning A System Setup Password

    CAUTION: Ensure that your computer is locked when it is not in use. Anyone can access the data that is stored on your computer, when left unattended. Table 39. System and setup password  Password type Description System password Password that you must enter to boot to your operating system.

  • Page 116: Clearing Cmos Settings

    Clearing system and setup passwords About this task To clear the system or setup passwords, contact Dell technical support as described at Contact Support. NOTE: For information about how to reset Windows or application passwords, see the documentation accompanying Windows or your application.

  • Page 117: Chapter 13: Troubleshooting

    Check diagnostics About this task SupportAssist diagnostics (also known as system diagnostics) performs a complete check of your hardware. The Dell SupportAssist Pre-boot System Performance Check diagnostics is embedded within the BIOS and launched by the BIOS internally. The embedded system diagnostics provides options for particular devices or device groups allowing you to: ●...

  • Page 118: Recovering The Operating System

    It enables you to diagnose hardware issues, repair your computer, back up your files, and restore your computer to its factory state. You can also download it from the Dell Support website to troubleshoot and fix your computer when it fails to boot into the primary operating system due to software or hardware failures.

  • Page 119: Backup Media And Recovery Options

    Backup media and recovery options It is recommended to create a recovery drive to troubleshoot and fix problems that may occur with Windows. Dell provides multiple options for recovering the Windows operating system on your Dell computer. For more information, see...

  • Page 120: Chapter 14: Getting Help And Contacting Dell

    Getting help and contacting Dell Self-help resources You can get information and help on Dell products and services using these self-help resources: Table 41. Self-help resources  Self-help resources Resource location Information about Dell products and services Dell Site Tips Contact Support In Windows search, type Contact Support, and press Enter.

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