Air cooling a pelt - do you still have to insulate the motherboard

[Egg]

Im running an athlon Tbird AXIA (i think it is) 1.2ghz
its not over clocked yet, and im at 36degress C idle at a 26 Degrees C room temp. Im using the thermo engine with a delta fan - the lound one :)

Im thinking of getting a small pelt, say 50 or 80 watt, and air cooling it with the thermo engine.

two questions - wot wattage ATX PSU will i need for a 50 and 80 watt pelt to run it at say, 12V. And what temps am i likley to expect

And will i still need to insulate the motherboard with silicon, dialetric greese and neoprene?

Thanks

[It_The_Cow]

Originally posted by Egg
two questions - wot wattage ATX PSU will i need for a 50 and 80 watt pelt to run it at say, 12V.
For a small one like those, a dedicated 250 or 300 watt power supply should do. If you plan to use it as a whole case power supply, a 400+ watt PSU would do depending on what you have in your case

Originally posted by Egg
And what temps am i likley to expect
Don't expect much. A T-Bird puts out 58 watts of heat. The general rule is to use a TEC rated twice as much as how much your processor puts out. So in the end, you'll probably end up making your processor even hotter
Originally posted by Egg

And will i still need to insulate the motherboard with silicon, dialetric greese and neoprene?

Thanks You don't need to insulate the motherboard, but it's highly recommended. Look around for tutorials and tips as to what to do

[Egg]

THanks for your reply, i have a dual psu case, im running a a 300 and a 250 watt psu now,
I might upgrade to a 550 watt to run my pelts and fans,
A 550 watt psu is rated at max 20Amps @ 12v so am i right in thinking this pelt will be ok?
Imax = 16.1 Amps
Qmax = 156 Watts
Vmax = 15.8 Volts
Delta Tmax = 69 (C)

THe only problem after that i can see is the thermo engine getting overloded, i will duct the air flow from the front of the case and perhaps stack a couple of deltas - ne thoughts?

[It_The_Cow]

Even the best heatsink wouldn't be able to cool a 156 watt TEC. Even if you run it at 12 volts, aircooling won't be able to disperse 112 watts of heat. For AMDs and peltiers, watercooling is usually the only way to go

[OddOne]

There's insulation, and then there's waterproofing.

With regard to insulation, I'd insulate everything on the cold side of the Peltier module with trimmed-to-fit layers of neoprene or similar so that the Peltier's only pumping the heat from the processor and not also trying to cool the surrounding air. This will improve efficiency by a noteworthy amount - a lot of folks pick up a few to several degrees C by insulating the cold side. This is a good idea for any active cooling system that can acheve colder-than-ambient cooling, Peltier included.

Condensation prevention measures (waterproofing the processor socket, etc.) are only necessary if any component on the cold side of your Peltier gets as cold as or colder than the ambient air temperature. If your case ambient is constantly 30 deg. C and your Peltier system chills the processor down to 25 deg. C, it'll be necessary. If your ambient is 30 deg. C and your processor never gets below 35, no need.

A 156-watt Peliter is outside the bounds for air cooling, which in most systems maxes out at around 100 watts contunuously assuming VERY good airflow. (A 156-watt Peltier is probably radiating about 220-250 watts of heat.) If you're going to use a Peltier that strong, you'll most likely need to water-cool its hot side, and the corresponding increase in thermal transfer efficiency from processor to ambient air will cause your temps to drop to well below ambient, and this will REQUIRE both insulation and anti-condensation measures.

An example of what happens when you take the time to research the subject at length and set everything up right:

I run a Peltier/water system on my P3-700. Intel processors don't radiate nearly as much heat as AMD's, to the tune of about 35 watts (estimated) from my P3-700E when run at 1035 MHz at 1.80V Vcore. I'm using a potted 80-watt Peltier being fed about 65 watts of power. My coldplate temps are almost ALWAYS sub-zero, and sometimes the coldplate gets so cold the motherboard's hardware monitor can't deal with it (read: colder than -40 deg. C! It rolls over from -40 to +1 deg. C.) My processor is usually sub-zero C when idling, and the coldest it's ever gotten was -18 deg. C. (All temps were taken from MBM 5 with a little tweaking for improved accuracy to match readings taken with an IR thermometer. So they're off by no more than +/- 2 deg. C.)

Because of those temps, everything is insulated like mad and the processor socket's backfilled with silicone dielectric grease. The insulation helped lower my coldplate temps and as a result, the setup's delta-T from ambient to coldplate averages 60-62 deg. C, with my standing record being 69 deg. C. (As in +30 ambient, -39 coldplate.) Thanks to insulation overkill, my coldplate has gotten to -50 C a few times (again, as read by a non-contact IR thermometer.

Another useful tip is to use thicker than normal layers of Artic Silver on both Peltier surfaces (assuming it's sandwiched between a waterblock and a coldplate) as the more of the Peltier's surfaces you have adequate contact, the better your system efficiency will be thanks to the increased transfer area.

One last tip: Run the Peltier from a dedicated supply, preferably a true independant 12VDC (13.8VDC ideally) supply as compared to a computer PSU. I use a Power One SPL1012-250 250-watt 12-15VDC adjustable industrial switching supply for mine as it can deliver 21 amps @ 12VDC, derating to 17 amps @ 15VDC, and is a rock-solid supply. You may be able to find them on eBay, which is the best way to acquire one - they sell for $345 new! You certainly can run a Peltier off a computer PSU (even the one the rest of the comp is fed by if the PSU is strong enough) but it's a lot more efficient and easier on all your components to keep the Peltier on its own supply isolated from the computer's.

That's all for now I suppse... :D

oO

[outhouse]

Nice post Oddone very nice.