Multi-GPU builds (2x4090 in 6 slots?)

[Etern4l]

Hello, quick question for anyone with multi-GPU build experience. Have people had any success running 2 slot cards next directly to each other (with no extra clearance in between)? What about 3 slot cards? I'm curious if 2 4090 FEs would fit and work reasonably well in 6 slots, particularly if not running under full load. This would have to operate 24/7 though.

[kojack]

If you had a good case, Can't see why note. Make sure to have alot of fans blowing into the case from the front and all should be fine. I was going to use two 2070 supers until I found out that Arc 770 will mop the floor with most anything for the work I am doing.  Who knows...But I think you should be fine running two if you have the room in the case. 

[Etern4l]

Yeah, so the question is regarding clearance. I can confirm 2.7 slot cards work well. 

[kojack]

Ahhhh gotcha.  I cannot help in that regard.  I would figure if they can be linked they would be designed correctly to take advantage of the slots available too.  

[Etern4l]

So the professional cards can be stacked easily, you don't necessarily have to NVLink them, depending on the application. The reason is they are usually 2 slots or less and don't use as much power. The problem is more with stacking those high-powered geforce cards. Imagine 2x600W 4090 FEs with no space between the cards. Temps? 

[kojack]

True. Plus the massive power supply you would need to run it all.  But imagine the power!  Would be fun! What kind of heat does one push?

 

[Etern4l]

Really depends on the config but obviously 1000W+ is easy. 

[MyPC8MyBrain]

On 10/10/2022 at 3:55 PM, Etern4l said:

I'm curious if 2 4090 FEs would fit and work reasonably well in 6 slots

one of our customers runs 2 x 3090, id imagine that physically 2 x 4090 can fit, 
but... second unit bus/lane speed, and power supply for 2 x 4090 may pose an issue, 

[kojack]

I wonder could you custom build a case with 2 power supplies in it?  have one for video cards and one for everything else?  Find the power on triggers in the plug and connect both supplies to it so you do not fry the board.  hhhhmmmmmmm Something to try on an old system 

[MyPC8MyBrain]

14 minutes ago, kojack said:

I wonder could you custom build a case with 2 power supplies in it?  have one for video cards and one for everything else?

you should be able to use two power supplies, server cases are prebuilt with two power supplies,

you mainly need a board supporting two power supplies less concern about the case itself,

some consumer cases also have space, it will come down again to your board,
for manual integration investigate how miners daisey chain their power,

[kojack]

I am just wondering if you can connect to the wires from the MB that triggers the power supply?  and nothing else?  would be an interesting experiment. I know there are server boards etc, but I am just using a plain old consumer board, figure out which wires on the main plug of the board turns on the supply and connect the second supply to that....

[MyPC8MyBrain]

sure you can you will need to either make the bridge yourself or get a splitter like this 

https://www.newegg.com/battleborn-131106131282/p/35Y-000B-00009?Item=9SIA85V3DG9612

as long as components don't draw power from both PSUs simultaneously you should be fine,

[kojack]

Awesome, didn't know this was a thing. Oh the video editing beast you could build....ha ha!