Multiple 40 Series GPUs in one Computer

[fredthelifeguard]

Budget (including currency): NA

Country: United States

Games, programs or workloads that it will be used for: Maya, 3ds Max, Blender, DaVinci Resolve

Other details: I work at a University and the animation department is wanting to upgrade their two render machines whose sole duty is rendering large animation projects as quickly as possible. They currently have a computer with 3 1080 Ti's and another with 2 2080 Ti's. They are excited about the new 40 series and the performance upgrade and they asked me if it was possible to upgrade to 3 4080s or 4090s for each system. From what I gathered, the cards are physically too large for the case to accommodate three 3-slot cards, but I am wondering now if even with a 1600w PSU you would be able to power two 4080s, let alone two 4090s. 

My question is, are reliable PSUs with greater than 1600 watts available? If not, is it possible to run two PSUs in one system, and what would the complications be with doing so? With the 4080 minimum being 750w and the 4090 850w, would it be possible to run two 4080s on one 1600w PSU with only about 100w of headroom for the CPU and everything else? Thank you!

 

[johnno23]

looking simply at the cost of 2 4080s and their perfomance drop from the 4090 your best soultion is actually a single 4090. cheaper and fast.

[DonGirses]

A multi-rail 1400W+ unit should be plenty for 2 4090s. When you get to 3 cards that's when it gets touchy and you might want to go for a separate power supply for the third card.

[tkitch]

So, what you're seeing is that limitation of standard electrical circuits.

 

Standard 110V Circuits are 20A, so a 1600W PSU is about 15 of 20A.  (And pulling more than that is risky due to wiring, or breaker potential issues.)

 

The only way to get 2K+ Watt PSUs is to wire them to a 200V Circuit.  At that point, yes, they exist.  (See the super sketchy 3400W PSU LTT Reviewed a while ago.  But don't buy it.)

 

[filpo]

5 minutes ago, fredthelifeguard said:

Budget (including currency): NA

Country: United States

Games, programs or workloads that it will be used for: Maya, 3ds Max, Blender, DaVinci Resolve

Other details: I work at a University and the animation department is wanting to upgrade their two render machines whose sole duty is rendering large animation projects as quickly as possible. They currently have a computer with 3 1080 Ti's and another with 2 2080 Ti's. They are excited about the new 40 series and the performance upgrade and they asked me if it was possible to upgrade to 3 4080s or 4090s for each system. From what I gathered, the cards are physically too large for the case to accommodate three 3-slot cards, but I am wondering now if even with a 1600w PSU you would be able to power two 4080s, let alone two 4090s. 

My question is, are reliable PSUs with greater than 1600 watts available? If not, is it possible to run two PSUs in one system, and what would the complications be with doing so? With the 4080 minimum being 750w and the 4090 850w, would it be possible to run two 4080s on one 1600w PSU with only about 100w of headroom for the CPU and everything else? Thank you!

 

two gpus for the 40 series aren't going to benefit as much as one. Better to go with one 4090

[starsmine]

Just now, filpo said:

two gpus for the 40 series aren't going to benefit as much as one. Better to go with one 4090

op isnt talking about SLI. 

[filpo]

10 minutes ago, fredthelifeguard said:

o run two 4080s on one 1600w PSU with only about 100w

 

3 minutes ago, starsmine said:

op isnt talking about SLI. 

ye but still 2 gpus

[starsmine]

7 minutes ago, filpo said:

 

you sure?

Im sure. The work OP is talking about is asynchronous. a second GPU, assuming CPU can feed both (it can) will close to half the seconds per frame/halve the total render time. We are not talking about real time here. We are not talking about real time here. One GPU does not care when the other GPU finishes a frame. it just moves on to the next frame the CPU sends it. 

Think toy story the movie, not toy story the game. 

[Agall]

10 minutes ago, fredthelifeguard said:

Budget (including currency): NA

Country: United States

Games, programs or workloads that it will be used for: Maya, 3ds Max, Blender, DaVinci Resolve

Other details: I work at a University and the animation department is wanting to upgrade their two render machines whose sole duty is rendering large animation projects as quickly as possible. They currently have a computer with 3 1080 Ti's and another with 2 2080 Ti's. They are excited about the new 40 series and the performance upgrade and they asked me if it was possible to upgrade to 3 4080s or 4090s for each system. From what I gathered, the cards are physically too large for the case to accommodate three 3-slot cards, but I am wondering now if even with a 1600w PSU you would be able to power two 4080s, let alone two 4090s. 

My question is, are reliable PSUs with greater than 1600 watts available? If not, is it possible to run two PSUs in one system, and what would the complications be with doing so? With the 4080 minimum being 750w and the 4090 850w, would it be possible to run two 4080s on one 1600w PSU with only about 100w of headroom for the CPU and everything else? Thank you!

 

The thermaltake 1650W comes with two 12VHPWR 600W capable connections, though I had a QC issue with mine and returned it. Ended up with the Seasonic Vertex 1200W. 

[fredthelifeguard]

So from the replies I am seeing here, it would be possible to run 2 4080s off of a single 1600w PSU but not recommended, because the performance gains from one 4090 would be minimal and would decrease system stability?

[starsmine]

6 minutes ago, fredthelifeguard said:

So from the replies I am seeing here, it would be possible to run 2 4080s off of a single 1600w PSU but not recommended, because the performance gains from one 4090 would be minimal and would decrease system stability?

honestly, I would be more worried about the circuit/breaker you plug it into then not being able to run it safely off of one quality 1500-1600W PSU. I wouldnt worry about the PC at all. 
 

[IkeaGnome]

6 minutes ago, fredthelifeguard said:

So from the replies I am seeing here, it would be possible to run 2 4080s off of a single 1600w PSU but not recommended, because the performance gains from one 4090 would be minimal and would decrease system stability?

The problem with these forums is that you’ll get a lot more of a gamer sense in answers. In games, no it doesn’t make sense. 
https://www.pugetsystems.com/labs/articles/1-7x-nvidia-geforce-rtx-4090-gpu-scaling/

 

4090s scale pretty well for normal workstation apps. I would probably stop at 2 but would be comfortable on a good power supply with it. Note they use total system power including a 5995x. 

[brob]

45 minutes ago, fredthelifeguard said:

With the 4080 minimum being 750w and the 4090 850w,

 

Total graphics power of an RTX 4090 is 450W. A system with two RTX 4090 would require 900W plus whatever is required to power the rest of the system.

 

As noted in the footnotes of the Nvidia specs, the 750W / 850W "Minimum is based on a PC configured with a Ryzen 9 5900X processor. Power requirements can be different depending on system configuration."

 

There are desktop motherboards that can support two 3-slot wide GPU offering offering 8 CPU PCIe 4.0 lanes each. Asus for example has the ProArt Z790 Creator and ProArt X670E Creator.

 

If you use pcpartpicker to create such a system you should find that a 1400W PSU is sufficient.

 

Using liquid cooled GPU would eliminate any concern with fitting two RTX 4xxx on an ATX motherboard.

 

[starsmine]

 

36 minutes ago, IkeaGnome said:

The problem with these forums is that you’ll get a lot more of a gamer sense in answers. In games, no it doesn’t make sense. 
https://www.pugetsystems.com/labs/articles/1-7x-nvidia-geforce-rtx-4090-gpu-scaling/

 

4090s scale pretty well for normal workstation apps. I would probably stop at 2 but would be comfortable on a good power supply with it. Note they use total system power including a 5995x. 

the important graph for others in here 

[SorryBella]

2 hours ago, starsmine said:

the important graph for others in here

Im not even a gamer and i get this. Being able to get more parallel compute units are more paramount in all of these apps but resolve. I agreed with 2 4080 but like yeah, the biggest issue is the fact that youre really limited to that 1600W on 120V power on most breaker. Youre going to need to consider installing an entire circuit just for that PC alone or even going for europe standard which is insanely hard to get installed by most US electric companies AFAIK.