PCI-E runs at x8 instead of x16

[_fess]

Hello,

I've recently updated BIOS to 0802 and GPU seems to have started running at "native x8 link speed." It used to always run PCI-E 3.0 @ x16, but now BIOS, GPU-Z and CPU-Z all show that it runs PCI-E 3.0 @ x8. Running GPU-Z render test or UNIGINE benchmarks doesn't help. It still shows PCI 3.0 @ x8. Clearing CMOS, reseating vid card didn't help. Running BIOS at optimized defaults didn't help. I'm running out of options here. Do you think I "broke" the mobo or vid card somehow or is it the BIOS issue. I hope it's the latter one. PC is only a month old and I had no issues with it until the recent BIOS update from 0505 to 0802. Here are my specs:

BIOS: 0802
OC'ed? No.
Motherboard: Asus ROG MAXIMUS X HERO (WI-FI AC)
CPU: Intel Core i7-8700K
AIO: Corsair H100i v2
RAM: Corsair Vengeance LPX 32GB (2 x 16GB) DDR4-3200
SSD: Samsung 850 EVO-Series 500GB 2.5"
NVMe (Boot): Samsung 960 PRO 512GB M.2-2280
NVMe (Games): Samsung 960 EVO 1TB M.2-2280
Graphics Card: Asus GeForce GTX 1080 Ti 11GB STRIX GAMING
PSU: EVGA SuperNOVA P2 850W

Thank you for your help!

[dyni00]

my mate not update bios/uefi never and have x16

[bojerka]

This is strange. I have same board like you and I updating BIOS (on latest) but don't have this problem. GPU still running on x16. I had this problem on old Z87-DELUXE board but I had too on that board GTX 1080. On Z370-F have 1080 Ti now.

[gdothello]

.fess wrote:
Hello,

I've recently updated BIOS to 0802 and GPU seems to have started running at "native x8 link speed." It used to always run PCI-E 3.0 @ x16, but now BIOS, GPU-Z and CPU-Z all show that it runs PCI-E 3.0 @ x8. Running GPU-Z render test or UNIGINE benchmarks doesn't help. It still shows PCI 3.0 @ x8. Clearing CMOS, reseating vid card didn't help. Running BIOS at optimized defaults didn't help. I'm running out of options here. Do you think I "broke" the mobo or vid card somehow or is it the BIOS issue. I hope it's the latter one. PC is only a month old and I had no issues with it until the recent BIOS update from 0505 to 0802. Here are my specs:

BIOS: 0802
OC'ed? No.
Motherboard: Asus ROG MAXIMUS X HERO (WI-FI AC)
CPU: Intel Core i7-8700K
AIO: Corsair H100i v2
RAM: Corsair Vengeance LPX 32GB (2 x 16GB) DDR4-3200
SSD: Samsung 850 EVO-Series 500GB 2.5"
NVMe (Boot): Samsung 960 PRO 512GB M.2-2280
NVMe (Games): Samsung 960 EVO 1TB M.2-2280
Graphics Card: Asus GeForce GTX 1080 Ti 11GB STRIX GAMING
PSU: EVGA SuperNOVA P2 850W

Thank you for your help!

I've had this issue with my Maximus Hero XI Mobo and 2080ti video card. I resolved the issue by simply resetting my bios settings back to default. I have no idea what setting fixed it but somehow along the way while trying to optimize stuff I must have mucked things up. Hope this helps.

[_H0PE_]

I've noticed while mucking around in BIOS last few days that my PCIE16x_1 primary slot with my rtx 2080 is on x8 speed.
At the time I only had two m.2 in the slots and no other devices connected to the mobo (other than cpu of course).
Is this normal behavior or I should see x16 for the slot?
Tuf Z370-pro gaming motherboard.

[Sathorn]

found a solution, posted there https://rog.asus.com/forum/showthread.php?120177-STRIX-z390-E-Gaming-PCIEX16_1-x4&p=813245#post81324...

[BB_Deluxe]

I realize this thread isn't for my mobo but appreciate the troubleshooting advice given and I'm happy some of you figured out a solution. Unfortunately, this issue is still affecting my X99 Deluxe ii motherboard with a new 3090 card. I tried to reduce bandwidth for all other PCI-E slots as well as use every auto combination method available and still no dice on PCI-E_1. It maxes out at x8. I have to use slot 3 for x16 speed.

My details were posted here ( 1070 now a 3090 😞 https://rog.asus.com/forum/showthread.php?91276-X99-Deluxe-II-Bad-PCI-E-socket-or-CPU-x8-native

[nonspin]

Even though it's a bit late, let me point out one little detail.. The difference between 8x and 16x is not noticeable. It certainly isn't "TWICE AS"-something.
Secondly .. and this is an experience thing .. and you can try it youself:
If you tighten the screw(s) (gpu) just a little bit too much, it'll change to 4x .. 8x .. 2x .. like a lottery.

[Wangeyed]

nonspin wrote:
Even though it's a bit late, let me point out one little detail.. The difference between 8x and 16x is not noticeable. It certainly isn't "TWICE AS"-something.
Secondly .. and this is an experience thing .. and you can try it youself:
If you tighten the screw(s) (gpu) just a little bit too much, it'll change to 4x .. 8x .. 2x .. like a lottery.

how tight your gpu is screwed in does not effect anything, i fixed this by removing the bios bat, clearing cmos jumpers didnt work.

[Stormwind81]

So this thread is a mess like no other.
I have an Rog Strix X299-E and having the same issue with a new 3080Ti.
It only shows x8 when it should 16x.
I have installed it via an riser cable that even supports PCIe x4.0 and my vendor is now asking me to send the cable back cause they dont have any idea either.

People reported they
a) put card in a different slot (reseating)
b) reseted bios
c) changed whole Motherboard

I am still not sure but at home I will try to reseat my GPU too.
In the bios it only shows x8 no matter what I try.
And I have 2 NVMe SSDs installed but why should they matter?

[Stormwind81]

Update:
I put my GPU from slot1 to slot2 of my PCIex16 and now it is showing x16 again.
Dont ask me why but it worked.