Whenever you cool something below the ambient temperature, you always have to worry about condensation, and since your using a peltier you have to worry even more since your CPU can go below 0ºC. Since we don’t wont to invite water into our computers to fry our components there are a few simple steps that we can take to avoid, or at least fight off condensation.
One, seal your peltier unit and copper cold plate (I’ll explain what this is later in the article) in CLOSED cell foam or a neoprene. The closed cell foam or neoprene seals your processor and peltier from outside air that way you don’t have condensation next or close to the cpu.
Now there are other places that we have to stop condensation from forming and that is on the backside of the CPU, and the backside of the motherboard or slocket.
To try and stop outside air from reaching the back of the CPU, we want to take a silicon-based rubber sealer (the more silicon the better). And place a bead of silicon around the outside of the socket and around the inside. This will stop the outside air from getting next to the backside of the CPU and will help prevent condensation.
Also take a piece of closed cell foam or a neoprene and put in the middle of the socket, this insulates the backside of the cpu from out side air that may get in and condensate on the backside of the cpu.
Ok so with the CPU pretty much insulated now we have to focus on the back of the slocket or motherboard. This is a very important step. You need to either take a neoprene patch (I would only use a piece of neoprene patch, I wouldn't use closed cell foam.) bigger than the area of CPU and glue it to the back of the motherboard or slocket. This would insulate the back of the motherboard or slocket from condensation, because it gets quite cool as well… Or you can get a can of "conformal coating silicone spray" and spray the back of motherboard or slocket heavily. This will have the same effect of insulating the backside of the slocket or motherboard and preventing condensation.
Also to help keep your CPU warm boot into the bios and turn off ACPI, or at least set the throttle/duty cycle to the max it will let you, on the BE6-2 the max is 75%. This will keep you computer from going into power saving mode and prevent your CPU from going below 0.
Ok early I mentioned a copper cold plate, so what is it? Well you never want to have direct contact between you CPU and your peltier for a couple of reasons. One Peltiers fluctuate in the amount of heat they can remove, so you need a buffer zone to keep cooling your CPU in your peltiers weaker moments, which is exactly what the copper cold plate does. The second reason why you use a copper cold plate is you need to spread the heat load from the relatively small area of the CPU die, to the whole peltier for max cooling efficiency.
Pic ripped from 2CoolTek.com
Now that we have covered all of the hardware things you can do to prevent condensation, lets look at the software things to stop condensation.
You don't want to tempt fate and let your CPU run at idle with your peltier running this will cause your CPU temp to drop down below 0ºC, which could allow condensation to form. So what is the solution to this? Well there are many programs on the net that will allow you to run your CPU at 100% CPU load one of these is the distributed.net client for RC-5. This little baby tries to break RC-5 64 bit encryption by brute force. It will eat up all of your spare CPU clock cycles keeping your chip warmer. Which lessens the chance of condensation forming… While you're at it why not sign up for the gideontech.com RC-5 team?
Another program worth taking a look at is Mother Board Monitor (MBM). This little gem is one of the best monitoring programs around and it also has a handy function built into it its called CPU Heat up, what does it do? Well if your processor falls below a certain temperature that you can set, it creates a thread in the cpu which use 100% of the operations which causes you cpu temp to warm up and after it reaches a temperature that you can set, its stops the thread and everything goes back to normal, that way if the program that you are using to keep your cpu temp up for some unknown reason crashes, well you won't end up risking frying your chip… MBM also has a shutdown function that will turn off your computer automatically if your CPU gets to hot, so lets say that your peltier fan dies, and as you CPU temp slowly rises, MBM can turn off your computer before it gets to hot to fry your cpu.
Note: MBM 5.x doesn't contain the CPU heat up function to my knowledge, only MBM 4.18 and lower contains it and you have to read the readme on how to enable it…
Ok now that you learned something about peltiers (hopefully) lets put it to good use and do some overclocking and extreme cooling. :-)