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brint

Classic Senior Dude
Joined
Dec 16, 2000
Location
Denmark
New at this...Need a little help

I have been thinking about getting a TEC unit, but I think I have to get a rather big one to cool my Prescott (478) 2,8@3,5Ghz down. 226Watt TEC I think will do the trick.

Watt = 78amps * 1,56volts = 121,68watts MAX!!
Watt = 40amps * 1,56volts = 62,4watts idle max.

eweast said:
Delta T = (1 - (Heat Load/Max Cooling Power)) * Max Temp Difference

*) Delta T = The actual difference in temperature between the hot-side and the cold-side that you should experience in the real world.
*) Heat Load = The heat generated (in this case) by the processor measured in watts.
*) Max Cooling Power = Maximum TEC rating in watts. (e.g. a 221-watt TEC or a 80-watt TEC)
*) Max temp = TEC’s maximum temperature rating in degrees C (theoretical Delta T, a.k.a. Delta T max).

[Originally written 2/9/03]


(1-(121,68/226))*67=Delta T= 30,9267
Cold side is 30,9267C cooler then the hot side.

(1-(62,4/226))*67=Delta T= 48,5009
Cold side is 48,5009C cooler then the hot side.

My 2,8@3,5 (1,56volts) is generating around 62C of heat under load and around 50C idle.

Maybe I should get a bigger TEC unit.......? Or what do you think?
 
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TEC+Prescott = Suicide in my opinion.

Way too much heatload after factoring in the flow surrouding the socket and an EXTREME amperage load for a peltier that is going to have to cool it.
 
L337 M33P said:
TEC+Prescott = Suicide in my opinion.

Way too much heatload after factoring in the flow surrouding the socket and an EXTREME amperage load for a peltier that is going to have to cool it.

I have been talking around with another guy and he thinks it will work.
Look at the Link and tell me your opinion.
 
brint said:
I have been talking around with another guy and he thinks it will work.
Look at the Link and tell me your opinion.

Yeah, you were getting good advice there. The key thing is your peltier is rated for more watts than your CPU is putting out. The peltier you have is rated for almost double the amout of heat your CPU is generating. As long as you can pull the heat off the hot side fast enough with your watercooling loop, you will be fine. If your radiator isn't large enough though, the heat will keep building up in your w/c loop. I had that problem the first time I fired up my TEC. I was using a horribly small radiator. No problems at all once I switched over to a heater core. http://www.ocforums.com/showthread.php?t=353511

Anyway, you should be fine with that peltier.
 
My honest opinion is that You should go with a phase-change system. A chiller might end up being less expensive than the TEC Unit, and would give you better temps.

The TEC will work, but I doubt your load temps will be very good.
 
sandman001 said:
My honest opinion is that You should go with a phase-change system. A chiller might end up being less expensive than the TEC Unit, and would give you better temps.

The TEC will work, but I doubt your load temps will be very good.

phase-change system? And what is a chiller? Not familiar with it?
 
brint said:
phase-change system? And what is a chiller? Not familiar with it?

Phase-change means using a liquid/gas that absorbs a lot of heat when it changes from a liquid state to a gas state. The gas in then condensed back into a liquid in a compresor and the cycle is repeated. Like an air conditioner/refrigerator/freezer. You can get colder temps with it than a TEC, but it is noiser. What temperatures would you like to get on your CPU? 10°C to 20°C, or -40° to -20°C? You are more likely to get the former with TEC, and the latter with a phase change system.
 
brint said:
phase-change system? And what is a chiller? Not familiar with it?

A phase change system is built around a compressor, like the one used in a refridgerator. Commercially, they go by popular names like vapochill and prometia. It is possible to build your own, and it would be a considerable challenge if you are not familiar with working with compressors. The easiest way to bring phase change into your cooling loop, and end up with temps better than that TEC can likely deal, would be to use a chiller. A phase change chiller uses a compressor to do the work, and the cooling coils would be submerged in the resevoir to cool the water. Typically they deal temps in the range between what was mentioned by the last poster.

A TEC system seems less far fetched to me, but the best results are had with phase change.

You will be able to TEC cool that prescott without a problem if you have a good watercooling loop... The temps may not be jaw dropping, but they will be very good.

I would look at the cost of each approach if I were you, and what sort of challenge you want, then decide which is more appropriate.

I have two final things to mention which I feel are worthwhile right now, to prime you so to speak:

A TEC operates most efficiently at about 80% VMAX. This means a TEC rated for 15Vmax is best operating at 12V in many cases. From 12 to 15V total cooling power does increase, however overhead increases far more than the total cooling power. If your cooling system is sufficient enough, 15V may yield the best temps for you; if it is struggling to keep up, you may find 12V is the place to be.

A final word about the temperatures you should expect - they vary considerably from theoretical calculations. There are many losses and variables concerned which are hard to calculate for - so take the math as a guide, but be prepared for the variance.

BTW, it is alway nice to see the old-timers return. I only hope that I will still be able to come back to this site for something years from now.
 
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A TEC system will be smaller, no doubt about it. You can make a very compact chiller, if you have the ambition. I can come up with some PLans for it, if you want. PM me for those.

You can make a chiller for under $200 pretty easily, a TEC system will be around there I think.
 
sandman001 said:
You can make a chiller for under $200 pretty easily, a TEC system will be around there I think.

What are you taking into that total? Depending on where you source the power supply, that could vary greatly, and could be closer to $100. PSU's with the amperage to power a TEC can be pricy, but if you can find a good grab on ebay, which happens from time to time, you can really save some buck.

I'm not thinking the rest of the cooling loop however, just the TEC, coldplate, and PSU, and some accessories. I would say depending on your luck, $100-150 would be my estimate. That isn't all that far off from the $200 figure.
 
I.M.O.G. said:
What are you taking into that total? Depending on where you source the power supply, that could vary greatly, and could be closer to $100. PSU's with the amperage to power a TEC can be pricy, but if you can find a good grab on ebay, which happens from time to time, you can really save some buck.

I'm not thinking the rest of the cooling loop however, just the TEC, coldplate, and PSU, and some accessories. I would say depending on your luck, $100-150 would be my estimate. That isn't all that far off from the $200 figure.

Well, tehnically, you could build one for under $130 most likely, but in order to make one compact, costs would go up some.
 
Cool, I've been out of touch with cooling for a while myself, so just wanted to make sure I wasn't missing anything. Thanks man. :)
 
I.M.O.G. said:
BTW, it is alway nice to see the old-timers return. I only hope that I will still be able to come back to this site for something years from now.

I started back in the day when the old forums were up and running, I think that was back in 1998 or something.

About my Water cooling, I don't think that will be a problem
My WC

I will try to think about all of this, I could be fun to use a TEC unit, it is old school :thup:

But thanks for the feedback so far guys.
 
I guessed that from the join date - all the guys who came over from the old forum have a start date like yours. ;)

I don't think that will be a problem either brint! :D Cheers on the nice setup.

If it were me approaching this, I would go with a TEC unit... Seems more fun and interesting for some reason, and I like the compactness of it better.

If you need any instructions on insulation requirements with a TEC, I think I have some old posts I could dig up for you.
 
brint said:
About my Water cooling, I don't think that will be a problem
My WC

I will try to think about all of this, I could be fun to use a TEC unit, it is old school :thup:

But thanks for the feedback so far guys.

Looking at that nice radiator, and the fact that you already have a TEC, I would say to go with that. You will have more than enough capacity to deal with the hot side of the peltier, and if you can find a used switching power supply with enough amperage on the 12v rails, it will be a very minimal cash outlay to get up and running. Just make sure to get Dow Conformal Coating and neoprene to insulate against condensation.

Looking forward to seeing what you do.
 
I.M.O.G. said:
I guessed that from the join date - all the guys who came over from the old forum have a start date like yours. ;)

I don't think that will be a problem either brint! :D Cheers on the nice setup.

If it were me approaching this, I would go with a TEC unit... Seems more fun and interesting for some reason, and I like the compactness of it better.

If you need any instructions on insulation requirements with a TEC, I think I have some old posts I could dig up for you.

I would like some aditional information on insulation, since I never have done anything like this before. I need a list of how to's and a material list, that would be great :clap:

torin3 said:
Looking at that nice radiator, and the fact that you already have a TEC, I would say to go with that. You will have more than enough capacity to deal with the hot side of the peltier, and if you can find a used switching power supply with enough amperage on the 12v rails, it will be a very minimal cash outlay to get up and running. Just make sure to get Dow Conformal Coating and neoprene to insulate against condensation.

Looking forward to seeing what you do.

Well I have not bought the TEC unit yet, but I think I will go with it anyway.
Like I.M.O.G. said, I like the compactness of it better. Plus I have always wanted to go extreem with a TEC unit.

I will keep you guys posted on the subject. Thanks for the help.
 
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