On-CPU Peltiers From AMD?

Hack Jandy writes "Remember those people who lived on the edge and put peltiers between their CPU and heatsink (or your favorite beverage)? A peltier is a devices that gets cold on one side and warm on the other when an electrical current passes through it. It looks like there is talk that AMD will actually incorporate some of these devices on the CPU according to Xbitlabs. AMD already incorporates some degree of the peltier effect with it's Silicon on Insulator."

What about reliability?

[Qzukk]

The problem with peltier coolers is that if it breaks down, the once cooling surface becomes an insulator. Plus, if the hot side gets too hot, the cooling process breaks down, so anyone using this would have to use a cooler that can draw the heat away as fast as the CPU-side peltier can kick it out, which would probably be another, larger peltier.

I'd rather stick to external cooling systems that I can monitor and replace if necessary.

Re:What about reliability?

[Pyromage]

The key thing with peltiers is that they just *move* heat. This can be more effective cooling because you can move heat from the CPU core (normally a very small area) to a much larger area. Yes, your net heat is a bit more, but you have a reasonably sized area to cool, which is a much easier problem.

The problem with todays chips

[doormat]

is not just the total amount of heat they put out, but the fact that they put out that much heat over an area of about one square centimeter (on the 90nm process at least). As the physical piece of silicon shrinks, the thermal density increases. More transistors switching on and off in a smaller area, and the drop in Vcc isnt enough to counteract the increase in density (we were at 1.8v or so with the 180nm process, and now at 90nm, we're at 1.4v or so - some chips dynamically change voltage and multiplier based on demand). I'm not sure this will do a whole lot of good if you just try to disapate the heat from the processor and the heat introducted by the peltier effect over the same square centimeter. You'd need to disapate the heat over a much larger area, say 10 sq cm. They you can stay in the realm of air-cooling instead of watercooling.

Re:What about reliability?

[gl4ss]

peltiers not really at 'effective' at that.

and let's stop here for a minute, simplifiedly.. a 100watt cpu, put some what, 250 watts(? or so) into the peltiering.. then you got 350 watts to get rid of 3 millimeters away from the original source!(you still need water & whatever to get rid of the heat)

with current efficiency it's only useful in extreme situations where you wouldn't mind such waste. it's only useful if you need such low temps for the cpu that you can't attain them otherwise!

it's not just a "bit more". and as for to getting it to a more reasonable area.. that's what heatsinks are for, that's what you would use anyways with the pelt setup to get rid of the heat(or watercooling or whatever, the point is you don't really spread the heat to a larger surface with peltiers).

Conservation of energy.

[leathered]

The key thing with peltiers is that they just *move* heat.

Which is exactly what your domestic refrigerator does, merely moves heat from the inside via the evaporator to the outside to the condenser. In fact heat cannot be destroyed at all (think conversation of energy), merely moved elsewhere.

Re:What about reliability?

[Cougem]

Erm, I fail to see how that's an argument. Just because you've got a hot side to cool doesn't mean it's a poor idea. A Prescott processor from Intel runs at an incredible temperature, how's cooling this any different from cooling the warm side of a peltier? Yes, you'll destroy your TEC if your cooling solution fails, but you'd crash before damaging your CPU, and you could apply that argument to any cooling sysyetm - if your CPU fan fails then you'll crash just the same.
Oh and I submitted this story two days ago and had it rejected.*Sigh*

Re:Stop confusing it's and its

[Anonymous Coward]

"Languages evolve. Deal with it."

Some evolution makes sense, some doesn't. The spellings and meanings of "it's" (= "it is") and "its" (analogous to "his") do follow the normal rules. Using "it's" when you mean "its" is about as sensible as using "hi's" when you mean "his".

Re:Peltiers?

[psetzer]

Finally, someone who actually does something to earn his handle.

Re:Power considerations?

[dbIII]

Consider a typical EER for a peltier air conditioner of 0.33 compared to 9.5 to 13 for a freon one. It's an interesting physical phenomenon, but a huge waste of energy.

First, you don't use it if you can just move gas around. Since it's just a couple of dissimilar materials in electrical contact at two ends it can fit in very tight spaces.

Second, the efficiency is going to vary enourmously depending on the temperature difference of the two junctions, so it's very hard to pick a number out of the air. In this situation you would first see if you could get away with copper and fins, then consider forced air convection, then other fluids or peltier. Since peltier is purely electrical it avoids the complications of moving fluids or gas around in another cycle - it can't move as much heat but gets the job done. The ideal is to have the computers in a climate controled room where humidity and temperature is not an issue (ie. have a big unit moving expanding gas around), but peltier get something done in less than ideal situations.

A very small peltier unit will alway draw less power than a pumped watercooled unit anyway, since you need a big enough pump to make things practical.