GPU not detected in upper PCI-E slot

[Nightbeat]

So I have an Asus P9X79 motherboard.

I have been running an GTX 970 WindForce for a long time now and it has been fine, however I decided to switch to 280X Vapor-X for some reason.

When I install the 280X in the same PCI-E slot the VGA LED is solid red and there is no signal to monitor.

When I put it in the bottom PCI-E express slot it works fine.

Anyone got any clue why the upper slot that worked fine for years to this day suddenly cannot detect the new gpu?

Currently my GTX 970 is in the upper slot doing just fine. The 280X only seems to work in the lower slot.

I try to put the 280X in another PC and it works fine.

 

[kn00tcn]

...on what bios version?? the release notes mention relevant fixes several times

historically, amd/ati have had new cards fail to boot on old mobos more often than new nv cards, usually the mobos have a bios update that fixes the issue, although your case is slot specific (is the lower slot a 2.0 slot?)

now you additionally need to consider the uefi settings, the bios could be set to disable legacy & the gpu might lack a uefi-enabled bios for example (sapphire actually posted or released some kind of uefi-enabled 280x or 7970 if i remember, also gpu bios modding will disable uefi support since it's no longer signed unless you do some trickery)

 

[Nightbeat]

...on what bios version?? the release notes mention relevant fixes several times

historically, amd/ati have had new cards fail to boot on old mobos more often than new nv cards, usually the mobos have a bios update that fixes the issue, although your case is slot specific (is the lower slot a 2.0 slot?)

now you additionally need to consider the uefi settings, the bios could be set to disable legacy & the gpu might lack a uefi-enabled bios for example (sapphire actually posted or released some kind of uefi-enabled 280x or 7970 if i remember, also gpu bios modding will disable uefi support since it's no longer signed unless you do some trickery)

BIOS version is 4801.

The bottom slot is PCI-E 3.0/2.0 x16 (x8 mode).

 

[basco]

i see one 6 to 8pin adapter.
did ya use it on the 280x.
i had probs with some