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PCI-E runs at x8 instead of x16

_fess
Level 8
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!
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52 REPLIES 52

Benson33 wrote:
*on the Asus website, to the support of the asus 1080 Ti, you have two different Bios, the original one and another silent mode with the integrated tool to flash the card, try to flash the bios of the graphics card to see if that can correct the problem.

Other thing, *did you make a clear Cmos after reflashing the bios of the motherboard and load seeting default ?


Hi
I know this is basic but when GPU is idle and in low power mode the slot speed can be reported as x8
try a program to kick the gpu into gear such as furmark or something you can watch the pci changing from x8 to x16

good luck

I had this issue and i did not understand what was wrong, and seeing your post confirmed the problem for me. I then saw somewhere that the 2nd 16x slot will cause the first 16x slot to go 8x if there is ANYTHING on that. I had a soundcard on mine and I moved it to the last one, which if I understand is controlled by the chipset. I confirmed that it showed up as 16X 3.0 on gpuz after.

Hopeywolf wrote:
I had this issue and i did not understand what was wrong, and seeing your post confirmed the problem for me. I then saw somewhere that the 2nd 16x slot will cause the first 16x slot to go 8x if there is ANYTHING on that. I had a soundcard on mine and I moved it to the last one, which if I understand is controlled by the chipset. I confirmed that it showed up as 16X 3.0 on gpuz after.


Yeah, that's would i do as well, but I have nothing on any of the pci-e slots and it still shows x8. I know for sure that ther'es something wrong with this card because I tested it on two PCs, Maximus X Hero 0802 bios and Z87-K with latest bios as well. The Z87-K pc runs with Asus gtx 760, wifi network card and a sound card all plugged in into pci-e slots. Abosultely no issues. GTX 760 is running at pci-e 3.0 @ x16. THe moment i plug the 1080 ti into it, bam, runs at x8 as well.

So yeah, two different 1080 TI's on two different computers, all run at 3.0 x8 and gtx 760 running at 3.0 x16 on both. I wish it was the other way around.

.fess wrote:
Yeah, that's would i do as well, but I have nothing on any of the pci-e slots and it still shows x8. I know for sure that ther'es something wrong with this card because I tested it on two PCs, Maximus X Hero 0802 bios and Z87-K with latest bios as well. The Z87-K pc runs with Asus gtx 760, wifi network card and a sound card all plugged in into pci-e slots. Abosultely no issues. GTX 760 is running at pci-e 3.0 @ x16. THe moment i plug the 1080 ti into it, bam, runs at x8 as well.

So yeah, two different 1080 TI's on two different computers, all run at 3.0 x8 and gtx 760 running at 3.0 x16 on both. I wish it was the other way around.


if there's any consolation, I have an issue too where I cant get pcie slot 3 to recognise my intel pcie 4x card. I tried 2 mobos. Hero and last year code. I ended up putting into second slot therefore dropping my 1080ti to 8x. Theres no bottlenecking due to slot speed.

vaiacondios wrote:
Hi
I know this is basic but when GPU is idle and in low power mode the slot speed can be reported as x8
try a program to kick the gpu into gear such as furmark or something you can watch the pci changing from x8 to x16

good luck


When the GPU is idle it alternates between 1.1 x8 and 3.0 x8, but never to 3.0 x16. BIOS, GPU-Z and CPU-Z, all three show the card running PCI-E 3.0 x8.
I ran furmark, unigine heaven, superposition for hours and monitored with gpu-z and hwinfo64 and it was locked at 3.0 x8 non-stop.

.fess wrote:
When the GPU is idle it alternates between 1.1 x8 and 3.0 x8, but never to 3.0 x16. BIOS, GPU-Z and CPU-Z, all three show the card running PCI-E 3.0 x8.
I ran furmark, unigine heaven, superposition for hours and monitored with gpu-z and hwinfo64 and it was locked at 3.0 x8 non-stop.


Are your 6 + 2 pin PCI E power cables properly connected to the VGA ports of your EVGA power supply? VGA1 and VGA2? try on VGA 3 and 4. I have a friend who had the same worries and by swapping his cables he found the PCI E X16.

Benson33 wrote:
Are your 6 + 2 pin PCI E power cables properly connected to the VGA ports of your EVGA power supply? VGA1 and VGA2? try on VGA 3 and 4. I have a friend who had the same worries and by swapping his cables he found the PCI E X16.


I'm pretty sure they are connected properly. Both lights glow white on the video card itself. Would they still glow white if one of the ports from the pci-e 6+2 wasn't working?

Update: I tried VGA1 and VGA2 and still showed x8. VGA3 and VGA4 yields the same results.

UPDATE #2: So i went to the store where I bought the card to test it out on their system and it worked no problem, it showed x16 and I saw it with my own eyes when they launched GPU-Z. So if the card runs properly on their computer I think I only have one conclusion - there is something wrong with the BIOS version. Let's recap:

1080 TI runs at 8x speed on Maximus X Hero with 0802 bios.
1080 TI runs at 8x speed on Z87-K with latest bios.
1080 TI runs at 16x speed on store's test system (not sure what mobo and bios they had).

GTX 760 runs at 16x speed on Maximus X Hero with 0802 bios.
GTX 760 runs at 16x speed on Z87-K with latest bios.

I guess I have to wait for the new BIOS revision, or may be there's something wrong with my motherboard.

Anyone else has this issue with their Strix 1080 Ti OC on Maximus X Hero?

Hi

Do you have any other PCIe cards installed?

Other cards? No. That my old mobo have "2 x PCIe 3.0/2.0 x16 (x16 or dual x8)" but second slot works only on x4 speed. This mobo now have friend with that 4790K and EVGA GTX 1080 and GPU run only x8.