Reduced Performance When Adding 2nd GPU

[legoyoda]

HI all,

 

I have a question for you folders... I've been trying to add more folding power by really utilising any space i have in any PC I have.   Testing by adding a 2nd GPU to my main system so see what uplift I cann get but it SEEMS to have slowed down my PPD and work rate for the machine as a whole Wondering if anyone knows why?> (A config issue perhaps, phantom PPD estimations etc).

 

System basics (before adding 2nd card):X570, R9 3900X (18cores folding), 32GB RAM, RX5600XT GPU
Producing about 1.5m-1.7m PPD

System basics (after Adding card)::X570, R9 3900X (18cores folding), 32GB RAM, RX5600XT GPU, Nvidia GP106 (mining) GPU

Producing.... about the same as above.... 1.5-1.7million PPD

I Can confirm that 3 x WUs are being worked on at once and my second PC running an additional 5600XT is now reporting that it is "outperforming PPD wise" the 5600XT in the main computer.  So, can / should I mix manufacturer GPUs in one system? does F@H need some odd config tweak to work like this?  Am I mad!?

Pointers on where to look appreciated.

Other things to note... both cards in PCI 16x slots with the primary GPU running 16X and the lower card sharing remaining lanes, All powered corrrectly from PSU (loaded to 75% so it's not out of power). Notionally, the slower card is 50% the speed of the faster one... which is in line witht he general GPU Hierachy.

[TheGlenlivet]

Is this a PCI lane issue?  I haven't folded in a while, but you went from x16 on the 5600xt to x8 when you added the second card, correct?

[legoyoda]

good point, I will check the BIOS to see how it's portioned out... I wasnt expecting folding to "required" the fill 16x

[Gorgon]

10 hours ago, legoyoda said:

good point, I will check the BIOS to see how it's portioned out... I wasnt expecting folding to "required" the fill 16x

A 5600xt certainly doesn’t need 16 PCIe x3 lanes. 8 would be fine under Windows.

 

The top 2 PCIe x16 slots in many x570 boards are wired to the CPU and when the 2nd slot is occupied they both go to x8/x8.

 

The third slot is usually connected to the Chipset and thus only has access to the shared x4 lanes from the CPU to the Chipset but even that should be just fine for an RX580.

 

I’d suggest removing the drivers and doing a DDU to really get rid of them then start again with just the 5600 and once you confirmed that works then try adding the RX 580.

 

Also try knocking back the number of threads for CPU folding down to 16 and see if that makes a difference. 18/24 with 2 GPUs should leave 4 for the OS and it should be fine but ...

[legoyoda]

Thanks everyone... Indeed, PCI lanes configuration issue (and me not understanding how they are split and what is connected to what.....  Appreciated and all now working as I would expect again.

[Rybo]

Interesting.  I've got two 1070's -- one running on an x16 lane, the other on an x4 lane, and they both get the same PPD (at least that's what my motherboard spec said -- I never did confirm in BIOS).  I just assumed folding didn't require big lanes -- just a lot of beef within the card itself.