Watter colling 4 x RTX 3080 Ti

[Cesar Villalva]

Hello everyone.

I would like to know if it is possible to watter cool four MSI RTX 3080 ti units with Corsair Hydro X products. I have no intention of water cooling the CPU

[LeDoyen]

it is, but you'll probably need either a massive case or external radiators.. And check the corsair configurator if they have waterblocks for your particular MSI model.

https://www.corsair.com/custom-cooling-configurator/gpu-search

If it's for a mining rig, i wouldn't go less than 2x 360mm radiators per pair of GPUs. Maybe two loops for 4 cards (better thermals and less downtime if any issue arises).

[Cesar Villalva]

Thank you very much for your answer LeDoyen. The utility is for scientific calculation, a code that runs on multiple cards and is intended to solve the behavior of water particles to perform simulations of the behavior in rivers, swamps, etc.
Although I have ever installed a liquid cooling solution, I have some doubts. Ok, I understand that I can put two circuits, but, can I use the same water pump for both circuits?

[LeDoyen]

I was hinting at two separate loops, 2 pumps, but you can start with one of course. I don't know how intensive the calculation is, if the cards get pegged at full power and generate a ton of heat for hours.

If that's the case, you could simplify and use a single loop, and experiment with various connexion methods.

In series, each GPU outlet feeds the inlet of the next one, so you warm up the water from GPU to GPU. Sounds bad but actually you may increase the temperature by 1 or 2°C per card if you keep the pump flow fairly high.

In parallel, each GPU is fed water from the pump (all waterblocks inlets connected together), and they all exhaust warm water together. No buildup from card to card, they all work roughly at the same temperature. Downside with 4 cards is that you need fairly high flow to feed the 4 blocks. 

The water temperature will be the same obviously since you dump the same amount of energy in.

Then pass the water through a series of rads, usually a common and slightly conservative rule of thumb is one 360mm rad per ~300W of heat. that's why i mentionned 4 rads, one per card. > back to the pump and off to the GPUs again.

You could use more radiators, or use thicker ones (like 45, or 60mm) to increase slightly the heat dissipation, and have less flow impedance. Thinner radiators slow down the flow more than thicker ones obviously, but may require beefier fans because you then increase airflow impedance.

It's a balancing act, and it's hard to predict what exactly is required for your setup.

I have no idea how a single loop will perform with 4x 3080Ti, but if you stick to soft tubing you can easily alter the setup to add a second pump and do two totally separate loops with 2 GPU each.

I personally would start simple : one single loop, one pump only, all in soft tubing, series loop and see how it performs.

last card too hot? try parallel or series/parallel

water too hot despite fans running hard : add more radiators

 

By the way, depending if you're doing open bench or a computer case, you may be able to use bigger radiators than 360mm. It's an unusual setup, so it may call for unusual solutions 😉

[c-attack]

Most of the critical information is covered above. If you are going to try for one pump + 2-4 radiators + 4 gpu blocks, then radiator choice becomes important. Radiators have varying channel widths and numbers which creates flow resistance at the split. Putting more than 2 narrow/high resistance radiators in-line is likely too much for this type of set up and I would not use something like a Corsair XR5 for this. Flow restriction is not something you’ll find on the radiator spec sheet, but will be covered in a professional review. Most radiators slot into a low/medium/high resistance category based on the channels. 
 

In addition to the flow resistance from the radiators and blocks, you also will have to contend with gravity. Hoping up and down in a normal case is a non-issue, but when you get into external solutions you may find you have a lot more vertical travel than expected. My external radiators are below the desk, but when combined with a very tall case I suddenly had a 4ft vertical rise to climb.  A second pump dramatically improved performance. This does not have to be a combination pump/reservoir and the 2nd pump only unit can be put into the loop in a logical place. 

Edited June 28, 2022 by c-attack