The BIOS performs memory detection and configuration with the following steps:
1. Program the buffer strength control registers based on SPD data and the DIMM slots that are
2. Determine the common CAS latency that can be supported by the DIMMs.
3. Determine the memory size for each DIMM and program the memory controller
4. Enable refresh.
8.3.4 Boot Error Codes
The BIOS provides visual and audible indications of a failed system boot by using the system's
power LED and the system board speaker. The error conditions are listed in the following table.
Visual (power LED)
Blinks red 2 times @ 1 Hz
Blinks red 3 times @ 1 Hz
nks red 4 times @ 1 Hz
Blinks red 5 times @ 1 Hz
Blinks red 6 times @ 1 Hz
Blinks red 7 times @ 1 Hz
Blinks red 8 times @ 1 Hz
Blinks red 9 times @ 1 Hz
Blinks red 10 times @ 1 Hz
NOTE: Audible indications occur only for the five cycles of the error indication. Visual indications
occur indefinitely until power is removed or until error is corrected.
Boot Error Codes
Processor thermal shut down. Check air flow, fan
operation, and CPU heat sink.
Processor not installed. Install or reseat CPU.
Power failure (power supply is overloaded). Check
storage devices, expansion cards and/or system
board (CPU power connector P3).
Pre-video memory error. Incompatible or
incorrectly seated DIMM.
Pre-video graphics error. On system with
integrated graphics, check/replace system board.
On system with graphics card, check/replace
PCA failure. Check/replace system board.
Invalid ROM (checksum error). Reflash ROM using
CD or replace system board.
System powers on but fails to boot. Check power
supply, CPU, system board.
Bad option card.
Technical Reference Guide