Question New computer isn't recognizing new GPU. But new GPU works in old computer and old GPU works in new computer.

[drewbagel423]

This is my old computer with an i5-4690K and 2060. This is the new computer I'm building with an i5-12400 and 6700 XT. When I try to boot up the new computer it isn't recognizing the GPU at all. Not in Windows (with HDMI connected to the motherboard and using integrated graphics). And not in BIOS - it just shows an empty slot. But the GPU fans spin.

If I take the 2060 out of the old computer and put it in the new one, everything works fine. Same when I put the 6700 XT into my old computer, everything works fine. I even tried swapping PSUs and power cables but that didn't make a difference. I've re-seated the GPU and cables several times. I tried with just one stick of RAM. I updated to the latest BIOS. I reset CMOS. Nothing works.

My BIOS has "CPU PCIe Link Speed" and "PCH PCIe Link Speed" settings with "Auto" and "Gen 1" through "Gen 4" options. I set it to "Gen 4" and the computer wouldn't boot at all so I had to reset the CMOS again. I didn't want to keep messing around with it since I don't know what I'm doing.

The only thing I can think of is that the 2060 is a PCIe 3.0 card whereas the 6700 XT is PCIe 4.0. But I don't understand why that would matter. I'm at a complete loss.

 

[ohio_buckeye]

You might try to manually set your PCI e speed to 3.0 while the 2060 is there. You could try 4.0 but who knows if the 2060 would keep displaying or not. It should work fine on auto settings, but who knows maybe that particular card isn't compatible to that board though it should be.

 

[DRagor]

The common problem now is GPU vs motherboard compatibility. Yes, in theory all four components you have should be compatible with each other no problem. In practice it is more and more common that they are not.
One thing you did not try is set PCH link speed to Gen 3, it works in some cases. Otherwise, you just need different model of either GPU or motherboard.

 

[drewbagel423]

The common problem now is GPU vs motherboard compatibility. Yes, in theory all four components you have should be compatible with each other no problem. In practice it is more and more common that they are not.
One thing you did not try is set PCH link speed to Gen 3, it works in some cases. Otherwise, you just need different model of either GPU or motherboard.

Wow that's wild that some motherboards and GPU aren't compatible. I did check on PCPartPicker and other people are using this same combination though.

 

[DRagor]

Wow that's wild that some motherboards and GPU aren't compatible. I did check on PCPartPicker and other people are using this same combination though.

Yes, but it's about specific combination of mobo model and GPU model. Partpicker marks them all as compatible because they should be, without actually checking if they really are. Like you know, nobody is going to cross check a 1000 different GPU models with 1000 different mobo models.

 

[LinuxDevice]

What you are describing is a signal failure (signal quality or operating at speeds not available to the PCIe device). I think @ohio_buckeye hit the nail on the head when suggesting PCIe v3 setting. However, if this does not work, then test at PCIe v1 and v2. Normally "auto" would be used, and during boot the PCIe device would go through "link training" whereby different speeds/standards are tested. The fastest available would be used, but if signal quality is not high enough, then this would revert to a slower standard. Failure would only occur if signal quality cannot work at v1 speeds. Not sure why auto would fail, but you might try manually setting to 3.0, then if this does not work, go all the way back to 1.0, and if that works, then try 2.0.

 

[drewbagel423]

Yes, but it's about specific combination of mobo model and GPU model. Partpicker marks them all as compatible because they should be, without actually checking if they really are. Like you know, nobody is going to cross check a 1000 different GPU models with 1000 different mobo models.

Right but I'm not saying Partpicker says they're compatible. I'm saying there are completed, working builds using these same parts.

What you are describing is a signal failure (signal quality or operating at speeds not available to the PCIe device). I think @ohio_buckeye hit the nail on the head when suggesting PCIe v3 setting. However, if this does not work, then test at PCIe v1 and v2. Normally "auto" would be used, and during boot the PCIe device would go through "link training" whereby different speeds/standards are tested. The fastest available would be used, but if signal quality is not high enough, then this would revert to a slower standard. Failure would only occur if signal quality cannot work at v1 speeds. Not sure why auto would fail, but you might try manually setting to 3.0, then if this does not work, go all the way back to 1.0, and if that works, then try 2.0.

Am I changing the CPU PCIe Link Speed or PCH PCIe Link Speed?

 

[DRagor]

Right but I'm not saying Partpicker says they're compatible. I'm saying there are completed, working builds using these same parts.

All it takes for it to work is different vBIOS version on GPU, so it is possible it works for them and not work for you.

Am I changing the CPU PCIe Link Speed or PCH PCIe Link Speed?

Depends where GPU is connected, if in top slot then CPU link speed.

 

[ohio_buckeye]

On the 6700xt, even if you did have to run at PCI e 3.0, you would not take a big hit from what I know. I'm using a 6700xt on an old b350 board with a 5900x(I get to install my new 240mm aio tonight But the videos I've seen on that card at 3.0 vs 4.0 show results that are basically even, maybe in favor of 4.0 by a few fps here or there but not enough imo to be too concerned about.

I'm a tech myself, and this reminds me of yesterday when I worked on a copier, I could not get the copier to talk on the network even though you could see the lights on the ethernet port flashing. It finally worked when I manually set the speed to 100 base T full duplex. Don't ask me why but for a copier that's getting a print job now and again who cares.

 

[LinuxDevice]

Right but I'm not saying Partpicker says they're compatible. I'm saying there are completed, working builds using these same parts.



Am I changing the CPU PCIe Link Speed or PCH PCIe Link Speed?

A bridge could in theory change speed to everything which is a device, while leaving the path to the CPU unchanged (sort of like a USB "trasaction translator") so far as I know. However, I don't know if that design only changes one, or if it changes both. It would probably depend on how many devices are shared on the bridge. If you were running under Linux, then you could probably extract some of that information via "sudo lspci" (and one or more options for verbose or tree format). I have no idea how to find that information from non-Linux hosts.