x16/x8/x4

DioOmicida · April 4, 2016

Picking up a lowerish end MB for an Intel build and want some clarifications on the PCIe. Copied from specs:

1 x PCI Express x16 slot, running at x16 (PCIEX16)
* For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot.
1 x PCI Express x16 slot, running at x8 (PCIEX8)
* The PCIEX8 slot shares bandwidth with the PCIEX16 slot. When the PCIEX8 slot is populated, the PCIEX16 slot will operate at up to x8 mode.
1 x PCI Express x16 slot, running at x4 (PCIEX4)
* The PCIEX4 slot shares bandwidth with the PCIEX1_3 slot. When the PCIEX1_3 slot is populated, the PCIEX4 slot will operate at up to x1 mode.

Does this mean if I had all three slots filled, the first two lanes would run at x8 while the third would run at x1?
So at most, I could run two GPUs and a x1 sound card and not two GPUs and a x4 PCIe SSD?

G27Racer_188 · April 4, 2016

It would be helpful if you tell us the exact M/B in quiestion.

devenson2017 · April 4, 2016

18 minutes ago, DioOmicida said:

Picking up a lowerish end MB for an Intel build and want some clarifications on the PCIe. Copied from specs:

1 x PCI Express x16 slot, running at x16 (PCIEX16)
* For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot.
1 x PCI Express x16 slot, running at x8 (PCIEX8)
* The PCIEX8 slot shares bandwidth with the PCIEX16 slot. When the PCIEX8 slot is populated, the PCIEX16 slot will operate at up to x8 mode.
1 x PCI Express x16 slot, running at x4 (PCIEX4)
* The PCIEX4 slot shares bandwidth with the PCIEX1_3 slot. When the PCIEX1_3 slot is populated, the PCIEX4 slot will operate at up to x1 mode.

Does this mean if I had all three slots filled, the first two lanes would run at x8 while the third would run at x1?
So at most, I could run two GPUs and a x1 sound card and not two GPUs and a x4 PCIe SSD?

You could do both options that you listed. THe last one wouldn't work though if you use a x1 slot as that will take bandwidth from the x4 bring it to an x1.