Dual 3090 Workstation.

[Balnazzar]

I have two Gigabyte Turbo 3090s, which I use for deep learning (read it as very high load for long time).
My case is the Define 7 XL. I already bought two alphacool waterblocks for my cards (exactly the same pcb as eagle/gaming).

I'd really like to know whether a thick (45/60mm), 420mm (140x3) radiator will be sufficient to cool them *while remaining silent*. I'll leave the cpu on air not to add additional heat to the loop.

Thanks.

 

[Eddy]

Hi,

3090 has more than 350W waste of heat, so 700W total. To have it silent, we say 100-120W for 120mm radiator surface. So a 420mm (doesnt matter wich thickness) is nor really enough. It will work, but not silent. So for a silent system, i would recommend 2x 360 ST30 radiators.
A XT45 instead of ST30 version will only perform better with low rpm fans if you use Push&Pull. With only Push or Pull the performance of a ST30 will be better.

 

[Balnazzar]

Hi,

3090 has more than 350W waste of heat, so 700W total. To have it silent, we say 100-120W for 120mm radiator surface. So a 420mm (doesnt matter wich thickness) is nor really enough. It will work, but not silent. So for a silent system, i would recommend 2x 360 ST30 radiators.
A XT45 instead of ST30 version will only perform better with low rpm fans if you use Push&Pull. With only Push or Pull the performance of a ST30 will be better.

Thick radiators, hence, perform better only in a pushpull fashion. That's interesting. And makes sense, now that you make me think about it..

And alas, I was afraid that I'd get that feedback about the rad. That's kind of a deal breaker, since for two 360s I'd have to open the ceiling, and that's allows a lot of dust to enter.
Besides, I understand that *all* the rads, no matter how big, would work as expected only if they draw fresh air from the outside, right?

 

[Balnazzar]

And, if you don't mind, another question. I've decided for an all-alphacool custom loop, except for the tubes. I will use EK ZMT 16/10 tubings.

Which kind of compression fittings do you suggest for those?

 

[Eddy]

You're also welcome to run it with a 420mm radiator, but as I said, it won't be silent. The PC 2 in my signature with the 1950X and the 2080TI is only cooled by a 360mm ST30 radiator. With light OC, that's a total of about 450-480W of waste heat that it has to cool down. If I put the CPU and GPU under full load at the same time, the fans have to run at around 1100rpm so that my temperatures remain in the green zone. The CPU goes to about 70° and the GPU to just under 60° at about 24° room temperature. These are not record values, but it works. I think with your two 3090 cards and the 420mm radiator it will look similar.
Ideally, the fans would suck in cool air from outside, but that doesn't make sense with your setup for various reasons. So stick with.... in the front and then out the top with the heat. No matter where you place the radiator. In the end, it doesn't make much difference as long as there is airflow inside the case.

 

[Balnazzar]

Very good, thanks. And what about the fittings?

 

[Eddy]

You can choose any compression fitting you like with the size 16/10mm. Thats up to you wich you like more.