Ryzen unstable with single graphics card

[Jim99]

I can't figure out what's going on here, so throwing it open to OcUK.

I have a Ryzen 1700 on an ASUS Prime X370 and 2*8GB Ballistix Sport (BLS8G4D240FSA.16FB), plus an ASUS GTX970 Turbo.

The GTX 970 is the part I brought over from my old Z68 machine, and has been working fine ever since I bought it.

However, with the new Ryzen PC I've had all sorts of issues. It would Prime95 OK, Memtest OK, and HDD check OK, and play a demanding game happily (e.g. R6 Siege), but suddenly crash when switching between games. Also, it would fail to boot 9/10 times.

At my wits end, I plugged in an old 5450 to run the second monitor as a sort of failsafe / backup, and suddenly everything worked.

Today I reinstalled Windows and ran GTX 970 + GT 210, and again it worked fine, but since NVIDIA drivers won't run both, I pulled it. Back to the same problem. Even running just one screen via DP wouldn't work. So I plugged in the 5450 again, and it's up and running again.

In summary:

GTX 970 running 1 screen -> Unstable and won't boot
GTX 970 running 2 screens -> Unstable and won't boot
GTX 970 running 1 screen plus GT 210 -> Stable
GTX 970 running 1 screen plus R5450 -> Stable
GTX 970 running 1 screen plus R5450 running 1 screen -> Stable

 

[Plec]

Have you tried the 970 not using a DP cable - i.e. just testing it with HDMI connections?

 

[Holst1981]

Something to do with pcix speeds?

Can you force a lower speed in bios?

Could be a bug with motherboard and drivers, unusual fault.

 

[Jim99]

Thanks both for your suggestions... cables didn't make a difference, but I have found that putting the GTX 970 in slot 3 rather than slot 1 makes everything work.

I'm reluctant to say it's a problem with the motherboard because otherwise it seems fine, but I can't think why else it would work in slot 3 and not slot 1. Nor why putting a card in slot 3 with the 970 in slot 1 would fix it.

 

[EsaT]

Third x16 slot (assuming X370 Pro mobo) is only PCI-e v2.0 with four lanes coming from chipset.
First and second x16 slots are PCI-e v3.0 slots sharing lanes from CPU.

So another card in third slot definitely doesn't change anything in PCI-e lane distribution.
(some other settings can't be exluded)
Did you try forcing first slot to PCI-e v2.0 mode from BIOS?