ThermoElectric (Peltier) Cooling

Wolfie

Anyone ever tried using Thermoelectric cooling? Seems to be more of a super-cool heatsink really, but wondering if they could in fact be used without a fan, and still provide sufficient cooling?

Here's a website in the States which sells em, and also seems reasonable for other mods... what with the exchange rate for the dollar et al. Although you still gotta pay import duty (probably).

Water cooling kits seem reasonable here too.

http://www.xoxide.com/?AID=10275116&PID=1338152

cheradenine

I think with peltiers although one side becomes very cold (to the degree that you can have condensation problems) the other side with all the shunted heat becomes very hot and unless you cool that the whole thing gets hot and you lose any cooling capability on both sides. The more poweful the peltier I presume the colder the cooling side gets and the hotter the other side, so you'd need more and more cooling, I was actually thinking about using one myself and attaching my watercooling to it to keep it cool.

daveJAM

The problem with peltiers is that they need power, so the hot side is not only the heat you've energy you've taken from the cold side, but also, the energy you've used in getting it from one side to the other.

Basically:
Energy on cold side + Power consumption of pelt = energy on hot side.

They're great for unlocking the potential of a watercooling system but if you want to use it for passive cooling, you really just end up with more heat than you had in the first place.

Wolfie

OK guys, thanks for the info. Guess I gotta get that ultra expensive water cooling system before using the Peltier cooling.

leeroybrown

I also think Peltiers are dodgy for cooling.

Afaik a decent peltier will draw somewhere between 80 -> 120 Watts of power from your PSU constantly. Thats a hell of a lot of power to be giving to it.

As stated above the peltier has one very cold side and one very hot side. This means that if you fail to provide adequate cooling to the hot side the cooling effect will quickly break down and your CPU will get very hot.

You need a lot of cooling on the hot side and by the time you deal with the heat the peltier generates you'll be spending the kind of money that will set you up with decent water cooling.

netman

Peltier cooling is a nice concept, fun to play with, usually ends up in a disaster.

I've been trying it out a few years ago, and to be completely honest it's not worth it. The risks and costs far outweigh the benefits. If you want an honest recommendation - go with watercooling. It's far less painful.

I was running a Peltier off the same power supply as the rest of the PC, so at least you can discard that as a problem. Get a decent enough power supply (400W+ these days) and you're set.

To get to the low temperatures on the cold side, you have to cool the hot side of the Peltier element sufficiently. You will need a lot more than just a conventional CPU heatsink for that, as you're not only dealing with the CPU heat, you're also dealing with the Peltier generated heat.

Another problem is the surface area. Processors generally have small cores, so small surface area. Peltiers are usually 40mm x 40mm or there abouts, so most of that "coldness" is going away unused. There's also no "buffer" when you really start burning that processor, the Peltier will constantly try to take away as much heat as it can (or produce as much cold as it can). That's why it's recommended to use a "cold plate" - essentially a copper plate between the peltier and the CPU which acts as a buffer. It can be cooled additionally by the Peltier because of it's larger surface, and will provide more temperature stability.

So now you have a big mofo heatsink and a couple of huge fans blowing on it, and you're faced with another problem. Where does that heat go? So you add a few more fans into the case to increase airflow, otherwise the whole thing becomes a furnace. And a 40-50C ambience temperature inside the case isn't an unknown where peltiers are concerned.

Once you think you've got it all sorted, here comes condensation !
You cool down the processor really well, in fact so well that it gets below ambient temperature, and water starts to condense on the cold plate and CPU. In general Peltiers are great when your CPU is at 100% work load. But here's what happened to me, I've set all of the above up, went out for coffee, came back and the screen was blank (power saving). Tried to turn the PC back up - no joy. Opened up the case and to my horror there was a trickle of water coming down the motherboard from where the CPU was. The AGP and PCI connectors have oxidised (sp?) but I got them cleaned. The CPU was still alive but the cache burned out. I did however manage to bring a 300 MHz Pentium II to a whooping 560 MHz. It was working at 500 MHz with air cooling, so the extra 60 MHz wasn't such a big step

And don't be fooled by people who will tell you to use neoprene and things like that. Only silicone will prevent condensation, and you will need to apply it inside the socket as well as around the CPU. You'll notice that the back side of the motherboard will get cold during operation, but I haven't experienced any condensation problems.

Now, with all the different watercooling kits commercially available at low prices I really don't see a need to dabble in Peltiers. They do become very effective when paired with a water cooling setup, as you can cool down the Peltier much better with water than you could with air, so it can reach even lower temperatures, but for the sake of a few MHz it's hardly worth the risk. Every time your Windows crashes you'll be struck with panic and taking apart the PC to see if there's any condensation flowing down your precious setup.

Having said all that, if you're still crazy enough to do it - it's great fun while it works good I'm afraid it won't win any ladies though, but you'll have stories to tell to the geeks of this world

Wolfie

Wow, great info Netman. Thanks for that. Think I will give Peltiers a wide berth, and file under "risky things to try folowing a Lotto win".

Cheers!

netman

Heh, with the way the technology is moving today it's hardly worth going into these types of cooling. You need to get everything well insulated to make sure you won't get any condensation problems, and it pretty much ensures you can't sell this to anyone afterwards.

This is what my Celeron 566Mhz looked like before insulating it: (I used silicone)
The picture shows a slot1 adapter, cold plate and an alpha cooler:


After insulation:


And when I took the whole thing apart:


No matter what you do afterwards, you can't clean it so well that people won't know you've been doing something funny with it

This Celeron got overclocked to 952 Mhz. The Alpha cooler used was a monster in those days. I dare not try to imagine what you'd need to cool a Pentium IV with a peltier.