PS3 fat still overheating after cleanup and reapp of thermal paste!?

I work in computer repair so should be able to fix this but I'm stumped. Overheating PS3, opened it up, it was FULL of dust, every crevice. All taken apart, all cleaned out, even inside the power supply. Reapplied thermal paste using spread technique (MX-2) and same problem. Did some research and then tried the Rice Grain method. No dice. Tried a method i saw on youtube: spread followed by pea sized dollop in the centre then bend upward the clamps that screw onto the heatsinks. No joy.

Last thing I tried was weird, reccomended by a mate. Spread the paste out over the edges of the processors, like spill it out over, plus a thin spread over the top. Needless to say that didn't work. Maybe it's not even the thermal paste thats the problem.

Now when I turn it on the fan kicks up its speed progressively after a minute or two then sounds like a jet engine and beeps and says it needs to turn off. Please help?