Is it worth it?

[Kensho]

Is it worth driving the coolant temperatures to the GPU and CPU down to 34 degree's F as opposed to air cooling at around 75 F room temp? I tried to find this information on the net but couldn't and came across this forum in my search. This will be my first build attempt and I've been wondering if doing something like this is worth it. I'm pretty sure I've got the condensation/dew point issues addressed, I was just wondering how much more performance it would generate in order to determine if it's worth it. How much more could I get out of a well built machine? The computer is going to be for video creation/processing, photo editing and graphic design work. By the way, cool forum...

[RONOTHAN##]

So you're talking about running ice water through the loop? Yeah it'll help with temps a fair bit and be able to get you an extra 100-200 MHz out of the CPU/GPU, but I wouldn't say it's worth it.

 

First, how are you gonna try to get the temps down that low? Every method I know of to have temps that low 24/7 and not just restocking ice involves some sort of phase change loop. If you're gonna go phase change, you're gonna be drawing a ton of extra power for maybe a 5% performance gain? And if you're going to be spending the money on some sort of phase change system, why stop at 34F, phase change coolers can pretty consistently get to about -20C assuming you use a good fluid, which should get you some actually noticeable performance improvements. 

 

Second, you said this is your first system. Custom water loops are advised for 2nd or 3rd computers, not first since custom water cooling is a fair bit harder than just building a computer in the first place, definitely not for a first system. The first system I built was water cooled with nothing fancy like phase change or having to insulate hardware, and it took me 2 days to complete it for just a soft tubing loop. Sub zero really only makes sense for benchmarking, for daily usage the headaches just don't justify the extra 3-5% gains you might see. 

[Kensho]

2 hours ago, RONOTHAN## said:

Every method I know of to have temps that low 24/7 and not just restocking ice involves some sort of phase change loop.

I do heavy commercial and industrial refrigeration for a living. I could drive the coolant temperature lower by running a glycol solution but you loose capacity as the specific gravity of the solution increases. I looked at some photo's and read a thread on a forum called overclocked where they went from discussing a singe stage to using a triple cascade system for 300+ watts of heat. This thread was from 2011. I don't get their calculations but they did seem to understand more than the fundamentals of refrigeration. At one point they were discussing temperatures around 45 C. That's -49 degrees F. At those temps, the refrigerant they were discussing using which was 404a, damn near operates in a vacuum in that temperature range. I'm guessing they were talking about expanding the gas(phase change) in the heat sink itself which is acting as an evaporator.The heat sink would have to be flooded or close to it in order to achieve capacity and that liquid would have to re expand into a cool gas before it reached the compressor in order to protect the compressor. I'm guessing that's why one of them suggested going cascade. You could pull it off with a properly designed single stage. It's an interesting project, it really is. Here's a question for you. What is the rough watt consumption of a high end GPU and CPU? Do the manufacturers this info?  And how much does it increase when you overclock these systems?

[RONOTHAN##]

1 minute ago, Kensho said:

What is the rough watt consumption of a high end GPU and CPU?

Depends on the exact CPU and GPU. 6950XTs are 330W at stock, 400+ when you unlock the power limits. 3090 Tis are 450W. For CPUs, if you're using a 12900K(S) they run at 300-400W depending on the exact load. For a 5950X they'll hit 200W before they become uncoolable. 

 

That said, with the way silicon works, the colder it is the more efficient it gets, so the power consumption numbers at ambient really don't matter when it gets cold and overclocked. Sometimes it gets way more efficient (12900K, for example, runs at 200W when fully overclocked when cold) and sometimes they get really power hungry (3090s, for example, if power limits are unlocked and you get full voltage control they'll draw 1000W+ given enough cooling). 

 

That said, GPUs only make sense to overclock when you manage to get full voltage control. With locked voltages you're not gonna realistically get any more performance by going cold, an extra 100-200MHz at most (not noticeable in game, important for benchmarking though). Because you need full voltage control in order for this to make sense, you have 2 options: 1.) buy a Kingpin edition GPU or 2.) hardmod the card.