GPU only runs at PCIe 3.0 8x and not 16x

[cmdrdredd]

Titale says it all, is this an incompatibility between the motherboard and GPU or something else? I've read some instances of this issue popping up on various motherboard and GPU combinations. I'm running an Asus Maximus X Hero and EVGA GTX 1080ti FTW3 card. I've tried both BIOS on the card itself via the toggle switch and the same behavior exists. I guess the actual performance isn't impacted much if at all according to my research into the issue but it's something I'd be interested to get to the bottom of if at all possible. I'm on the latest BIOS for both the GPU and Motherboard by the way.

I've tried re-seating the card, clearing the CMOS and starting over in the BIOS for the motherboard. I doubt it's software related because the BIOS also reports it's running PCIe 3.0 Native 8x but I've reinstalled drivers as well. GPU-Z also reports it as PCIe 3.0 8x and I have set the performance target for windows to high performance and don't have any power saving features enabled in the nvidia control panel. Finally I noticed that the Nvidia control panel says it's running on PCIe 3.0 16x bus. So I don't know what's going on. It's the only PCIe card installed and I am not using any M.2 drives.

 

[sze5003]

The only thing I can think of is it it in the x16 slot? The x16 slot is usually the one that's far right.

Can you take a pic of how it's currently seated?

You probably tried thratest bios.

 

[cmdrdredd]

Yeah it's in the right slot lol. If I didn't look, I'd probably be none the wiser about it either. Apparently even a 1080ti isn't saturating PCIe 3.0 8x bandwidth so a single card isn't going to get a benefit from a full 16x slot. I have seen reports on the ROG forums about this happening with other people. Some never did find a fix. For now I'm going to leave it unless I find a quick fix of some kind.

 

[sze5003]

I did some browsing too and saw another thread where other users had the same issue. One guy ended up having a bent CPU pin that ended up fixing it. Now you have me wondering if I should check my mobo too. Pretty sure dxdiag is reporting x16. Seems to be an issue with this motherboard, the hero edition I guess.

Do you have any other expansion cards in the other pcie slots?

 

[moonbogg]

I remember GPUz mentioning something about the GPU has to be under load in order for the full PCI status to be shown sometimes. There is a benchmark button on the bottom right that stresses the card and shows the PCI-E status. Did you use that button?

 

[cmdrdredd]

I remember GPUz mentioning something about the GPU has to be under load in order for the full PCI status to be shown sometimes. There is a benchmark button on the bottom right that stresses the card and shows the PCI-E status. Did you use that button?

Yes and no change. I’m happy with the performance I’m getting. Everything seems to be in line with expected results.

 

[Guru]

Check in your BIOS if you actually have 16x pci-e enabled. You can actually change the transfer rate in a lot of these bioses and you could have lowered it to 8x by accident. Other than that, try and update to the latest bios and see if that helps.

 

[whm1974]

Its my understanding that current GPUs don't use the full bandwidth of x16 slots anyway and that there plenty of room left for much higher performance future GPUs.

 

[cmdrdredd]

Check in your BIOS if you actually have 16x pci-e enabled. You can actually change the transfer rate in a lot of these bioses and you could have lowered it to 8x by accident. Other than that, try and update to the latest bios and see if that helps.

Have the latest bios and there is no option to change the link speed, I can only select gen 1, 2 or 3 or set it to auto.

 

[cmdrdredd]

Its my understanding that current GPUs don't use the full bandwidth of x16 slots anyway and that there plenty of room left for much higher performance future GPUs.

That’s what I had read as well which is fine. Like I said the performance is great at 8x.

 

[moonbogg]

Well congrats on the new card. I wouldn't mind doing some benchmark comparisons with you if you'd be in the mood. I'm wondering what difference I'd see with a faster CPU. Maybe we could do a GTAV benchmark run or some other stuff. I duno, might be fun to mess around and compare the two rigs to see any difference the 8700K makes vs 6800K. It could help me determine if I should care about getting a faster CPU any time soon.

 

[UsandThem]

It might be a bug, so I would send an email to their support team, and maybe they could fix this issue with a BIOS update. It's rare, but I've seen this sort of thing a few times over the years where a motherboard and video card don't play nice with each other. The nice thing for you is yours actually works (albeit in 8X mode). But like you mentioned already, it doesn't really affect performance right now since PCIe 3.0 bandwidth isn't fully saturated (tapped out) by today's video cards.

 

[cmdrdredd]

Well congrats on the new card. I wouldn't mind doing some benchmark comparisons with you if you'd be in the mood. I'm wondering what difference I'd see with a faster CPU. Maybe we could do a GTAV benchmark run or some other stuff. I duno, might be fun to mess around and compare the two rigs to see any difference the 8700K makes vs 6800K. It could help me determine if I should care about getting a faster CPU any time soon.

Yeah lemme know what you want me to run and at what resolution and settings etc in a PM and I’ll do it.

 

[Carfax83]

Has to be a conflict of some sort. The only thing I can suggest is to try and fiddle with the UEFI link gens if you haven't done so yet. Try setting it to 3 and then check if Windows is registering the proper speed, and then to auto. Auto should automatically default to PCIe 3.0x16, but if there is an issue with the UEFI, you might have to manually set it to gen 3.

 

[Carfax83]

Well congrats on the new card. I wouldn't mind doing some benchmark comparisons with you if you'd be in the mood. I'm wondering what difference I'd see with a faster CPU. Maybe we could do a GTAV benchmark run or some other stuff. I duno, might be fun to mess around and compare the two rigs to see any difference the 8700K makes vs 6800K. It could help me determine if I should care about getting a faster CPU any time soon.

bogg, an 8700K wouldn't be a good upgrade from your current CPU. That's more like a sidegrade if anything. Both of them are hexcores, and while the 8700K has a massive clock speed advantage and a slight IPC boost, the difference in performance won't be that noticeable unless you run predominantly single threaded apps or games.

And when you consider the whole Specter nonsense that's going on, that's even more reason to just wait until Intel manages to completely mitigate the performance hit. Personally, I'm not upgrading my platform until complete Specter performance hit mitigation, PCIe 4.0, and maybe even DDR5.

 

[cmdrdredd]

bogg, an 8700K wouldn't be a good upgrade from your current CPU. That's more like a sidegrade if anything. Both of them are hexcores, and while the 8700K has a massive clock speed advantage and a slight IPC boost, the difference in performance won't be that noticeable unless you run predominantly single threaded apps or games.

And when you consider the whole Specter nonsense that's going on, that's even more reason to just wait until Intel manages to completely mitigate the performance hit. Personally, I'm not upgrading my platform until complete Specter performance hit mitigation, PCIe 4.0, and maybe even DDR5.

The performance hit for on specter is minimal and within margin of error. I have tested both ways. Unless you have NVMe SSD drives you should not see any real difference at all. Games and the like show zero impact for me. I only use SATA SSDs so the I/O difference isn’t noticeable.

I think you are right though a 6800k to 8700k isn’t much of an upgrade to me either. I came from a 3570k and z77 system with SLI 970s to a 8700k and 1080ti which I must say was a very large jump. Still the more info you have as a consumer the better so if moonbogg is curious I am totally willing to do some benches.

 

[Carfax83]

I came from a 3570k and z77 system with SLI 970s to a 8700k and 1080ti which I must say was a very large jump. Still the more info you have as a consumer the better so if moonbogg is curious I am totally willing to do some benches.

Yeah that's a huge upgrade to be sure. Enjoy your new system man!

*Edit* You need to update your sig. Nothing is more fun than updating your sig when you get new parts!

 

[sze5003]

Checked my board..seems like it says running at x16 native. Must be something off with the hero board only. At least it's still running at full speed and working properly.

 

[cmdrdredd]

Well, I fixed it...the fix made me feel incredibly stupid but it's a good reminder. Check your PCIe connectors. What happened was the serial number sticker EVGA puts on the PCB that attaches to the connection pins at the bottom of the card was actually covering some pins. This caused the link speed to drop down of course since it wasn't detecting a proper connection. ALl is well now though. Don't know why I didn't check, guess I never thought a serial number sticker would be there when there is one on the back plate a few inches above the connector. Messed with overclocking but gains are so minimal for the increased voltage required and extra heat. Using the overclock BIOS to get a higher power target though but it never really clocks higher and it doesn't seem to change the clocks when I attempt to go +30 on core. The memory moves but boost remains the same. Probably just gonna leave it stock, no patience to get a few benchmark points lol

 

[Carfax83]

Yeah I agree. Enthusiast motherboards typically can display PCI-E link speed when something is plugged into the slots. Even mine does, and I'm on an older X99 board.

It's extremely odd that cmdrdredd's motherboard does not. I reckon he should contact Asus customer support and see what they say.

 

[sze5003]

Well, I fixed it...the fix made me feel incredibly stupid but it's a good reminder. Check your PCIe connectors. What happened was the serial number sticker EVGA puts on the PCB that attaches to the connection pins at the bottom of the card was actually covering some pins. This caused the link speed to drop down of course since it wasn't detecting a proper connection. ALl is well now though. Don't know why I didn't check, guess I never thought a serial number sticker would be there when there is one on the back plate a few inches above the connector. Messed with overclocking but gains are so minimal for the increased voltage required and extra heat. Using the overclock BIOS to get a higher power target though but it never really clocks higher and it doesn't seem to change the clocks when I attempt to go +30 on core. The memory moves but boost remains the same. Probably just gonna leave it stock, no patience to get a few benchmark points lol

Damn that was it! I've had a similar issue with the PSU currently in my system. One of the pins that goes to the 8 pin CPU socket was covered by the connector on the PSU wire since it was one of those wires that splits into multiple connection. Completely missed it and had to unassemble and plug that in first when I swapped mobos. Was freaking out when I couldn't figure out why the PC would not post.

Glad you got it figured out. Strange your mobo does not display pcie slot status. I would think since yours is a more expensive board you would have more options than my board in bios.

 

[cmdrdredd]

Damn that was it! I've had a similar issue with the PSU currently in my system. One of the pins that goes to the 8 pin CPU socket was covered by the connector on the PSU wire since it was one of those wires that splits into multiple connection. Completely missed it and had to unassemble and plug that in first when I swapped mobos. Was freaking out when I couldn't figure out why the PC would not post.

Glad you got it figured out. Strange your mobo does not display pcie slot status. I would think since yours is a more expensive board you would have more options than my board in bios.

It does, but it always said 8x, until I found out about the sticker. What I said before is you cannot manually set the PCIe link speed. You can only manually set which gen it runs at, not toggle between 16x and 8x

 

[Guru]

It does, but it always said 8x, until I found out about the sticker. What I said before is you cannot manually set the PCIe link speed. You can only manually set which gen it runs at, not toggle between 16x and 8x

That is essentially changing the speed. Gen 3 runs at 16x, gen 2 at 8x and gen 1 at 4x.

 

[LTC8K6]

That is essentially changing the speed. Gen 3 runs at 16x, gen 2 at 8x and gen 1 at 4x.

Yes, that's essentially true.
https://en.wikipedia.org/wiki/PCI_Express#History_and_revisions

 

[cmdrdredd]

That is essentially changing the speed. Gen 3 runs at 16x, gen 2 at 8x and gen 1 at 4x.

No you can have a gen 2.0 x16 card. The bandwidth might be the same but you can’t tell the motherboard to run at PCIe 8x instead of 16x and you can’t tell it to run 2.0 16x which does exist in older cards.