Peltier theory

dragon2309

dragon2309

P.I Dragon
i am seriously considering getting a peltier to use on my system, i ahve drawn up a quick diagram in paint of how i think it would go, is it right and what temps could i expect to see with a cpu averaging at about 38 C with standard water cooling, delta T is -69.

peltdiag1ux.jpg
 
what temps could i expect to see with a cpu averaging at about 38 C with standard water cooling,
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Depends on the TEC performance curve(s) as well as the water cooling performance (delta T of -69 doesn't mean much taken out of context). Do you have a link to the TEC manufacturer?
 
Erm... i tyied to find the actual manufacturers site but i couldnt, its this one here http://cgi.ebay.co.uk/350Watt-Peltie...QQcmdZViewItem
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Can't really make any predictions about the performance without data. I'll poke around for some other TEC performance curves and try to extapolate back to yours.

Also, i was reading up a bit and a few people have mentioned shoving a copper cold plate inbetween the CPU and the pelt, i take it this is to spread the CPU's heat out, do i actually need one???
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Yes, you'll definitely want to get one - that TEC is 60mm x 60mm which is much bigger than the CPU heat spreader. The TEC surface is ceramic so it won't conduct heat very well from the area that is not in contact.

You should also put some thought into how you're going to power it. TEC are incredibly power inefficient and take quite a bit of power; definitely a separate power supply.
 
Ok, the seperate power supply, i have a bit of cash now so i can afford to get another one, just how would it connect though, just wire it into the motherboard power connector or what??
 
Ok, the seperate power supply, i have a bit of cash now so i can afford to get another one, just how would it connect though, just wire it into the motherboard power connector or what??
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Connecting the TEC leads? Probably just the +/- 12V off the 4-pin molex. If you really wanted to go all out you could buy a variable voltage/current power supply since the TEC might not (well, it most likely won't) get full performance from 12V.
 
oh ok, well that helped aswell, but i actually meant the second PSU, how would you make it turn on at the same time with everything else....?

Any luck with finding anything out about that pelt??
 
oh ok, well that helped aswell, but i actually meant the second PSU, how would you make it turn on at the same time with everything else....?
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There's a way you can wire it up to switch the additional PSU on... might have to splice some wires. Never actually had to do it myself.

Any luck with finding anything out about that pelt??
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Well, if the 350W is cooling power, and both the cooling power and max delta T are constant (which they aren't, lower CPU temp = decrease TEC performance) I figure that a CPU running at 100W thermal (a bit high maybe) and a waterblock maintained at 25C (probably hard to achieve, need a very good radiator) would get to about -25C. This is probably an upper bound on the performance.

Stick a fan on top too, just for that added protection! Just like a double johnny bunk up!
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Wouldn't do much good, TECs put out butt-loads of heat :)
 
How about a huge lump of copper running out into a bucket of water outside the case?! :D

Im being silly now...... Ill stop now :P
 
There's a way you can wire it up to switch the additional PSU on... might have to splice some wires. Never actually had to do it myself.
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that is a relatively easy task, you just need one simple relay, a single pole double throw will do it. Wire up 1 molex from PSU1, across the relay control inputs, and wire the psu_on pin (usually the green pin) of PSU2 and a ground pin (any black one) to the throws of the relay.
When PSU1 turns on, it will send the 12v of the molex high. This will activate the relay, which will short psu_on with the ground, sending it low and turning on the PSU2 as the same time.

Should work, found this relay quickly, its got a higher current tolerance and switching capacity than you need, but it will be big enough to work without a PSB

edit: I drew a little picture of what i mean
 
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what about condensation?
"or was this questioned earlier?"
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Nope, that's something that dragon2309 will have to address. Can be taken care of with some good insulating foam and dielectric grease.
 
Okidoki, all seems relatively simple., not a quick job thoguh... one thing, i dont have a case that supports 2 PSU's, any ideas?? (and its VERY cramped in there as it is).

Insulation isnt a problem, would you explain that grease stuff, how it works and where is should put it??

dragon2309
 
Insulation isnt a problem, would you explain that grease stuff, how it works and where is should put it??
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This site will explain better and more in depth than I can do in a post:http://www.vr-zone.com.sg/?i=224&s=1
Okidoki, all seems relatively simple., not a quick job thoguh... one thing, i dont have a case that supports 2 PSU's, any ideas?? (and its VERY cramped in there as it is).
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That's where a little creative modding comes in handy (or take the easy, but expensive, way out and buy a new case :P)
 
im guessing this wotn work unless your using water cooling?

i cant just drop my thermaltake o nthe top of this and call it cold ?
 
im guessing this wotn work unless your using water cooling?

i cant just drop my thermaltake o nthe top of this and call it cold ?
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Not unless it's a really good HSF. Peltiers can bring the cold side below ambient, but as an expense they produce much more heat than the CPU alone would. So you would need a HSF capable of handling a lot of heat.
 
Riteo, i shall look into all of those differnt things, price up and see what happens. Thanks for all your help, i'll be back
 
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