Can I run two folding cards without a pcie x8/x8 motherboard?

[mattheginger]

So I'm currently scoping out my first new build in 10 years, in which I hope to run 2x 4070 Supers. But I've noticed that only the high end motherboards support pcie x8/x8 these days. So my primary question is whether that actually matters for folding? What would happen if I installed two cards into a standard b650 or x670 board? Would they run x16/x4? (x4 through chipset). Would they run at x4/x4? And if I could run the top card at x16 and the bottom card at x4, would x4 (through the chipset) provide sufficient bandwidth for folding?

 

I require the top card to help me slay in Battlefield   So it needs at least 8x.

 

Any help would be appreciated 

[Robchil]

why?... 40 series has NO SLI support... at all..  you'll get more out of it if you combine the cash for those two cards and get a single better GPU that use all 16 lanes. 

 

[DoctorNick]

40 minutes ago, Robchil said:

why?... 40 series has NO SLI support... at all..  you'll get more out of it if you combine the cash for those two cards and get a single better GPU that use all 16 lanes. 

 

SLI isn't used in folding or any mining for that matter.

And to answer the question: yes you can run on lower speeds, you might loose some performance, but running 4x or higher should be OK, considering it'll run 4.0. Check manual for PCI-e/M.2 config @mattheginger

[mattheginger]

17 hours ago, DoctorNick said:

And to answer the question: yes you can run on lower speeds, you might loose some performance, but running 4x or higher should be OK, considering it'll run 4.0. Check manual for PCI-e/M.2 config @mattheginger

Thanks for your reply. So I should be able to retain 16x on the top card, whilst running 4x on the bottom?

[DoctorNick]

4 hours ago, mattheginger said:

Thanks for your reply. So I should be able to retain 16x on the top card, whilst running 4x on the bottom?

Idk check the manual

[mattheginger]

@Gorgon Do you have any knowledge in this area? Have you built any multi-GPU 5000 or 7000 series Ryzen rigs? Cheers.

[Gorgon]

Due to the cost of the DDR5-based systems I'm still running mostly x570 with Gen4 x8/x8 from the CPU.

 

Unfortunately from what I recall only the b550 Vision D and Vision D-P were the only two low cost motherboards with x8/x8 from the CPU (i.e. with PCIe Gen4 switches) with 3-slot spacing. AFAIK all the b650 motherboards have only x16 from the CPU and all other slots are x4 from the Chipset and most of those are Gen3 as the PCIe Gen5 Re-Drivers and Switches are hellishly expensive and Motherboard manufacturers seem to be focusing more on lots of M.2 slots.

 

Still if you can find a b650 motherboard with PCIe Gen4 from the Chip Set at x4 that would be equivalent to Gen3 x8 and so you shouldn't loose too much yield with "just" a 4070, But most b650 motherboards appear to have just PCIe3 x1 to the Chipset connected slots so your likely stuck with having to get a 670 or 670E which are waaay more expensive.

 

The other option is to go off-label and get a PCIe Gen4 m.2 -> PCIe x16 adapter and use the CPU-connected m.2 slot for the second GPU and install the OS on one of the Chipset connected m.2s. But then your stuck with trying to figure out how to secure the second GPU.

[mattheginger]

Thanks for your input @Gorgon. I think perhaps I'm just going to take the easier route, and step up the main GPU I put in my primary system to some form of 4080. It wont quite match 2x4070s, but I guess it'll be close enough and with less complication  

[gravitywave]

You'll definitely lose some performance running a modern card at 4x off the PCH. It's not like cryptomining where the bus width and latency doesn't matter so much. One of my boxes runs two cards, and it's got an EVGA Z590 board I got on deep discount. I picked it because not only would it do pcie 4.0 x8/x8, but it also has extra space between the 1st and 2nd physical x16 slots than is typical--helps with cooling for sure. I'd just keep an eye out for deals on boards that fit your requirements and jump when the opportunity comes up. I wouldn't go pay full retail for a high end board for this.

[Roflwaffle17]

I run a gen 3 card in the first slot and gen 4.0 card in the second slot on a platform that only offered gen 3 slots. The gen 4 card is an A2000 and it only loses around 1% performance after the gen 3 downgrade and x8 downgrade. It really does depend on the card, lower end cards don't really care unless you are running it in a crypto mining setup with x1 slots or something. For 4070s, the x8 slots should be good enough honestly and I would expect an average of like 3-4% drop in performance provided you are on a gen 4 platform. Definitely would take a bigger performance hit from thermals or something else. 

[Gorgon]

Doing some research for something else I surveyed the x670e motherboards to see which ones have PCIe5 x8/x8 slots:

 

About the only "reasonably" priced x670e boards out there are the Asus ProArt and Strix x670e-e and the ASRock TaiChi. The MSI Carbon WiFi would be a contender but rather than shifting all the PCIe slots down 1 slot like the rest they decided to shift everything down 2-slots meaning the lower card will, in most cases, collide with the PSU Shroud.

 

Gigabyte appears to be avoiding having to buy re-drivers on their 670e motherboards in favor of even more m.2 slots and so are out of the running. Which makes me wonder why the Extreme and Master are so expensive.

[mattheginger]

On 3/11/2024 at 5:26 AM, Gorgon said:

Doing some research for something else I surveyed the x670e motherboards to see which ones have PCIe5 x8/x8 slots:

 

About the only "reasonably" priced x670e boards out there are the Asus ProArt and Strix x670e-e and the ASRock TaiChi. The MSI Carbon WiFi would be a contender but rather than shifting all the PCIe slots down 1 slot like the rest they decided to shift everything down 2-slots meaning the lower card will, in most cases, collide with the PSU Shroud.

 

Gigabyte appears to be avoiding having to buy re-drivers on their 670e motherboards in favor of even more m.2 slots and so are out of the running. Which makes me wonder why the Extreme and Master are so expensive.

Thanks @Gorgon. Yeah I did look at both the ProArt and Strix models, but in the end decided to just build a B650 system. And perhaps I'll chuck a 40 series card in my old Ivy bridge system at some point, which my new build has now made redundant. 

 

Interestingly though, I'm now getting significantly better numbers from my 4070 (non-Ti) in the new system. The card is now topping out at 97% utilisation, whereas before it never surpassed ~92%. This is netting approx an extra 1.5m PPD on the average WU. Could be the difference between PCie 3.0 vs 4.0 perhaps?