Peltier Cooling advice please

milltown

Apologies to the mods for double posting this, it was barely getting looked at on the tech board and I was unable to delete it.

I am planning to have a play around with a 72w peltier in an air only cooling setup. Plan is to machine a pure copper heatsink to fit in the pelt and run a high speed fan on top.

Would I need some form of cold plate between the pelt and the CPU, if so what material would be best? Or is it ok to have the pelt in direct contact with the CPU?

How likely is it that the hot side of the peltier will melt the copper heatsink and turn my cooling project into central heating for my PC?

Any advice from anybody who has tried or read about this type of thing would be handy.

CPU is Athlon XP2400 tbred btw.

BabyEater

A 72 watt pelt would be no use to a 2400XP it would do your graphics card tho. For an overclocked CPU you would want a good 220Watt pelt as theCPU would be putting out at least 100Watts and you need double that wattage.

If using a more powerful pelt like this you would be better with water. If you want to use your 72Watt on a GPU then try and make your cold plate from copper far better than aluminium .
It wont get that hot that it will melt your cooler.

jow

Originally posted by BabyEater
A 72 watt pelt would be no use to a 2400XP it would do your graphics card tho....

It wont get that hot that it will melt your cooler.

not to mention: a gpu won't melt down when you do an error wiht the installation

If your cooling is unsufficient (and when you do your first experiments with a peltier that is likely ... peltiers are a _little_ tricky) your graphics will crush down, but normally this does no harm to the gpu.

when you don't cool your AMD cpu it will be destroyed within seconds :ninja:

ah ja: and don't forget to isolate your installation. if you don't do that you will get some condensation in your case... not so nice for the components.

I have a test of the "ready_to_use" Thermaltake Peltier Cooler (Subzero 4G).
The result is: Forget it! It cools a XP3000+ only to 55 degrees, and that is a result you will easily get with an normal copper cooler.
The problem is: when you have to cool for example a xp3000, which produces around 74 watts, the peltier produces heat itself (the test said around 160W). So you need a very good cooler to get rid of the 160watts! Thats why that thermaltake thing isn't very good and has a very noisy fan installed.

Have fun an post your results!

jow

milltown

Thanks for the news I didn't want guys

Would I not be right in thinking that any extra cooling would be of benefit to the CPU or is it a case that anything above the 72w would be prevented from being tranferred away from the chip by the pelt?

jow

Originally posted by milltown
Thanks for the news I didn't want guys

No problem, we are experts in giving useless advices

Would I not be right in thinking that any extra cooling would be of benefit to the CPU or is it a case that anything above the 72w would be prevented from being tranferred away from the chip by the pelt?

Yes that is the point: You have no extra cooling with a 72w peltier!
Thats what we try to explain you.
The amount of energy being transfered by the peltier is 72w. A xp produces more than that. So all you get is: a warmer (maybe burned) CPU and on the other side (a peltier does not transport, or does transport additional heat very badly), your copper cooler has to transport more heat than mounted directly on the cpu.

As far as I understand: a peltier cools with a limited range. Extra heat will not be transfered through the peltier (like with copper coolers).
A peltier cools on one side and heats on the other and normally you have to put more energy in than you get out for the cooling process.

regards

jow

Virus_Inc

Peltiers only shift their rated wattage in heat, in itself a peltier is actually a really good insulator which is why you have to be careful with them, if yer peltier dies so does your cpu.
Also have to mount peltiers properly so you don't get condensation = really bad for electrical stuffs....

netman

also keep in mind that when you're looking at specs you need to find out at what voltage does that peltier have 72w. it could be 24 volts for exampe, and if you're hooking it up to a 12v molex connector it might only give you half of that. (it's not linear though, so you should be checking the manufacturer's specifications)

figuring out what you need is the first step. radiate is a nice freeware program that will tell you how much heat your processor is producing. then look at getting a peltier that has at least that much wattage at 12v. you'll definitely need a "cold plate", that comes in between peltier and your cpu/gpu. it's not recommended to put the peltier in direct contact with the cpu, as the contact area is very small and you're just loosing efficiency.

also, proper insulation is a must. especially if you're doing this to a cpu, which can potentially get very cold in an idle state, and very hot when running at full load. condensation is bound to happen, and the only way to do this properly is by insulating the open area with silicone. i've tried foam, rubber, gaskets etc, they all caused condensation, sometimes inside the assembly which you cannot see until you remove all the parts.

i've played around with this quite a lot, and it's great fun but the results aren't that great and there's always a risk of the peltier failing and your cpu getting burnt in seconds. water cooling is a much better option, if done properly it's really no risk and all gain.