Update:
I put some work in this weekend. I disassembled the PS3 and replaced the thermal pads and paste.
Motherboard front.JPGMotherboard back.JPG
I discovered something strange, but good, when I took the heatsink off. The RSX heat spreader was missing! The heat sink looks like replacement for the OEM and is better designed, in that it contacts the RSX die and memory directly, without the heat spreader. I was debating whether or not to take it off because the process can delaminate the memory, but I don't have to mess with it at all...Nice! I did not come across this setup anywhere in my youtube or google searches. Wierd. In any case the thermal paste (arctic cooling MX-4) is non-conductive so it being near the caps on the RSX is ok, especially as I removed the heatsink after the first application to check my method was effective, and it was.
I drilled holes in the bottom of the case just aboave the fan to allow cool air to flow directly in. I used a sunflower seed pattern which utilizes the "golden angle" of 137.5 degrees to maximize space. Basically, the pattern exploits Fibonacci numbers geometically to optimize airflow. It seems to work really well; it gets plenty of suction.
Vent Pattern.JPG
I placed the temp probes (much more difficult than I was expecting) in a less than ideal location on the underside of the board because of the low clearances and way the board sits. I'm not happy with it and will probably move them again eventully, but for now I will just focus on finishing the build.
I still need to install the 19 blade fan, the temp monitor/controller, and tap into a power source. I did not realize the fan connector was not standard (although I should have known.) I could still make an adapter out of the old fan's connector, but instead I will go ahead and tap into the blueray connector as I need 12v, 5v, and ground for the controller. As for the fan, I will probably splice in a regular 3pin connector, but keep the original attached so it has both. This way I can choose to connect it to the controller or the motherboard. Just waiting on the fan to get here...