EVGA Z790 CLASSIFIED User Manual page 21

EVGA Z790 CLASSIFIED (121-RL-E798)
* PCIE slots are referred to by an "x" followed by a number, such as "16", which can
refer to one of two things:

The slot's mechanical design (the physical length on the motherboard)

The slot's electrical design (the number of PCIe lanes available to the slot from
the CPU, PCH, or both).
Motherboard specs will often reference both the length of a PCIe slot and the number
of available lanes. While it is easy to visually determine the slot length, you cannot
determine the bandwidth available by sight alone. Generally, the PCIe slot length also
determines the maximum number of lanes available to the installed device.
PCI-Express was designed to be universal. For example, you can install x1 form-factor
devices, such as sound cards or USB controllers, into an x16 length slot. The x1 device
will be capped at x1 bandwidth, regardless of the slot's electrical characteristics.
On the other hand, shorter PCIe slots may limit the types of devices you can install. For
example, a motherboard may have an x4 length slot. If the end of the slot is closed,
then you will only be able to install x4 length devices, or shorter. If the x4 length slot is
open, you can install a longer PCIe device, such as a full-length graphics card. However,
the maximum bandwidth of the slot will still be limited to x4, in this example.
Lastly, a PCIe x16 slot with Gen5 x16 lanes means that the slot is theoretically capable
of providing full Gen5 bandwidth. It is unlikely, that you will achieve this, however.
PCIe devices work as an on-demand type of component, and only utilizes bandwidth
necessary to accomplish its task. Even gaming and compute applications rarely push
graphics cards to the upper limits of PCIe Gen4 bandwidth at the time of print.
To simplify the mechanical compatibility of the Z790 CLASSIFIED, this motherboard
supports:

PE1 – supports x16 PCIe devices or shorter.

PE2 – (with M.2 heatsink installed) supports x4 PCIe devices or shorter.

PE2 – (without M.2 heatsink installed) supports x16 PCIe devices or shorter*.

PE3 – supports x16 PCIe devices or shorter.
For the electrical compatibility of the Z790 CLASSIFIED, please see Page 23.
*The PE2 slot can support PCIe devices up to x16-length if the M.2 heatsink is
removed. However, use of an M.2 device with a tall pre-installed heatsink in the M.2_3
slot may block installation of devices longer than x4 length.
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