I'm using a 1.25" thick 2x2 block of aluminum for the layer between my CPU and peltier. Really, copper needs to be 3/8" to 1/2" to spread the effectiveness of the peltier to the top of the core. Aluminum has to be about 30% thicker. I had to clear some mobo components, so 1.25" worked out pretty good.
Last night I did most of the work of the installation. The only serious problem was that I poured to large of a plug in that area in the middle of the CPU socket (I used hotglue--a very good electrical insulator). It was about .75mm too tall and wouldn't allow the CPU to seat entirely correctly. When removing it, I popped off a resistor and had to re-solder it with a small soldering pencil. Hopefully it made good contact.
My 2nd goof was that when I was hotgluing the top of the motherboard with a thin coat around the CPU socket, I forgot to leave the CPU retention clip holders bare. I was going to use thin sheetmetal to make a custom bracket to help apply pressure to my heatsink assembly. Now, I'll either have to dig them out (not a fun process) or just do without and hope I can trust the foam to hold it down (Great Stuff).
I drilled holes in my aluminum block and sandwitched my peltier in between the heatsink and cold block with two screws. I know it made good contact because I actually cracked off part of the peltier (small section of top transfer wafer--not the actual peltier).
Lastly, I used silicone to apply about 1/2" to the area around the CPU on the back of my motherboard. It covers about 1" out from the CPU pins. This should do a good job of stopping any condensation. Since I'll have to wait a day for it to cure, I'll get back to the job tonight, when I can build a foam former for the spray foam and shoot it with Great Stuff. I will also be attaching an 80mm fan to the hot side's heatsink. Once that stuff sets up, I'll be firing up the mobo and hoping it works. It may not run at all since I broke the resistor.
