Why doesn't my system run cool ?

[muffy]

i have a p4 2.5

with water cooling

i have 2 radiators one glacial radiator and one smaller radiator and a aluminum water block running 3'8's piping. I also have a peace of copper between the cpu and the peltier

i purchased a 172w peltier to make things a but more interesting. from what i have read i was expecting to get sub zero temps

however at best i can only get 17c . after doing some research i found that the 172w peltier is meant to be running @ 24 Volts even though it comes with a plug to plug into a normal 12volt psu ? so after putting an ammeter into the loop i found it's only making 62w's @ 12volts not 172w's, So i bought a 24 volt psu and now the peltier runs at 172w's however it still only cools the cpu to 17 ish degrees and im at a complete loss as to why

if i completely remove it from my system and place the peltier 's hot side to the water block and leave the cool side in the air it simply doesn't get that cold ? ( as in much below ambient )

the water block and water does not seem to get warmer than ambient temps. from my understanding if the cold side is 17c that would make the hot side about 86 degrees ! which seems a bit hard to believe when the water doesn’t seem to get warm

what im asking is why doesn't it work properly ?

[bigben2k]

Probably for lack of clamping.

Can you give us details of your setup, including a water temp, and composition?

[muffy]

um no clamping ?

do you guys use thermal grease

[bigben2k]

Thermal grease is optional, but probably better.

Your pelt is not clamped at all? That's a problem...

http://www.procooling.com/articles/h...__just_how.php

[Phant0m51]

Question...

Isn't it true that TEC's have a sharp curve after like 75% max voltage? And that using the max voltage creates extra heat with little performance gain? If it's true, then maybe that extra heat isn't getting dissapated and is going back into the cold side, keeping it from getting as cold as it could.

Just a thought.

[bigben2k]

Originally posted by Phant0m51
Question...

Isn't it true that TEC's have a sharp curve after like 75% max voltage? And that using the max voltage creates extra heat with little performance gain? If it's true, then maybe that extra heat isn't getting dissapated and is going back into the cold side, keeping it from getting as cold as it could.

Just a thought.

Not quite.

Above 80% of the voltage, the heat transferred increases very little, so there just isn't much point. The extra power applied still needs to be dissipated, which will increase the water temp, essentially unecessarily.

[MadDogMe]

Don't use Artic Silver type heatpaste with TECs!!. It dries out and becomes useless. Use Generic White Silicon type heatpaste with TECs. TECs need to be clamped between the waterblock and coldplate at just over 100~PSI for optimal thermal~interface, the CPU clamping pressure is 24~PSI (I think), there's a big difference no?...

if i completely remove it from my system and place the peltier 's hot side to the water block and leave the cool side in the air it simply doesn't get that cold ? ( as in much below ambient )

If it's not 'frosting up' when it's out of the case there's something very wrong with the TEC or the power supply(or your H2o block is 'uber shyte' ). Seeing as you've tried two PUS's I'd say it's the TEC. Bin it and get a 220watt TEC, it'll run off 12v though (15V v~max so 12v is the most efficient). How many amps is your 24v PSU rated for?, it has to be around 30amps continuous rating(this is judging by a 220watters needs). If it says 30amp MAX it probably is'nt putting out enough as that will be it's'Peoples~Republic peak/spike falling off a cliff while being struck by lightning' rating ...