Waterchilling + Pelt??

[M.Beier]

Would it give a major boost to use TEC + waterchilling... - I got -30 / -25 deg water... - Would I benefit from a 226W pelt on my x850XT?? - Only for benching... - It could be quite fun it it was posible to hit -55 on the cold side... - But would it??

Ofcause I'd have to use a PSU for the pelt, and nothing else... - But thats no problem :)

Hope to get some great featback from all ya experts!!

Thanks,
Marc

[ilkkahy]

I love to see chiller+peltier setups. Heatload is huge which your compressor propably cant handle so the liquid temps will raise slowly (unless the chiller really has kick in it). I dont know what X850 heatload is but im sure 226w peltier can take it. Even though peltiers efficiency gets worse at colder temps.

[M.Beier]

28 liters of water at -30 takes some time to warm up :)

Its a 450W (575W at boot up I think...) compressor, with a neat gas mixture ;)

The problem is... When TEC's performs worse when they're cold... - And load/idle is extreme while using TEC (15 deg delta Tload Tidle, with vmod on gfx...)

[mikeguava]

I did a quick test before with a TEC getting -60C on the hotside - it helped to get the temps even further down - but the lines powerlines were starting to melt within seconds.

Your Delta T will get worse and worse the colder the hotside gets - and I have a feeling that -30 might be potentially the max cold you should/could go, but possibly a bit warmer would be better.

As a rough guess -30C watercooling on the hotside ( hotside pelt temps will be around -15C) - would give you -40C on the coldside when idle - but capcity will still be pretty weak.

+3C water temps can give you about -10C finishing temps after a 3DMark05 bench on a overclocked X850XT with a very strong 250W pelt

[M.Beier]

So no pelt's the best?

with -9 deg water, it gets around 0 deg idle, 18 deg load... - With -30, it'll properly be around 0 deg C, load....

[mikeguava]

Sorry - I wasn't clear - Pelt is still better - just the Temp drop differential will get smaller and smaller with the hotside of the pelt get cooled better.
While you have a 50C idle differential with ambient water temps when idle - you'll just get a much much smaller differential once the hotside is getting minus degrees cooling.

I am by no means a TEC expert - only have some limited experience with them. In the TEC setup that my friend ViperJohn had made I have a temp probe for both hotside and coldside TEC temperatures which allowed me to get a very good overview on how well the TECs were doing.

Here's a very rough comparo how things would approx. perfrom in my case:

Ambient:

Water temp : 28C
Tec Hotside: 35C
Tec Coldside: -20C
Gpu Idle: -18C
GPU 10min load: +5C

-> GPU vs Water Temp Delta T under load: ~ 23C

Chilled water:

Water temp : 3C
Tec Hotside idle: 16C
Tec Coldside idle: -38C
Gpu Idle: -35C
GPU 10min load: -10C

-> GPU vs Water Temp Delta T under load: ~ 14C


SUberzero cooling pelt:

temp : -60C
Tec Hotside idle: -50C
Tec Coldside idle: -65C
Gpu Idle: -64C
GPU 10min load: ???

-> GPU vs Water Temp Delta T under load: ~ 10C - and a pelt will probably burn up within a few seconds... would love to hear other user experiences on this - I only tired once it it was a bust!

[Holst]

Generally if you have a compressor big enough to cool a big peltier to -30 on the cold side the same compressor tuned to only cool the CPU (much much lower wattage) will hit lower temps than with the TEC in place.

If you have some other source for -30*c water (like siberian winter) then a pelt chiller might be better.

Most of the time phase change is better without TEC, otherwse all the guys in the phase section would be using them. None of them are... this should tell you something!!