PS3 Eraser Mod
Original Forum ThreadEraser Mod is an alternative to delidding the CPU package. It works by putting an eraser piece in the hole behind the CPU, what this makes is it increases the pressure applied to the package evenly, and mitigates the old dried thermal compound inside the CPU package. It may seem like increasing the pressure on the CPU package may tire the motherboard and break the traces, but this "fix" is actually official, some models of PS3 already come with a plastic piece attached into the hole, so even Sony thinks this is fine to do. The only required tools are a screwdriver to open the PS3, and some sort of knife to cut the eraser into the shape. You can actually use any kind of eraser, soft or hard, contrary to what is said in the original forum thread. I have tested both. The model I used here is a CECHL.
The forum thread says 3.5mm thick eraser for FAT models, and 3mm thick for SLIM models. The forum thread also says that soft erasers won't work but I have tested it and it works the same if you add 0.5mm more thickness as it gets squished more. PLEASE DO NOT USE ANY THICKER ERASER, THICKER DOESN'T MEAN BETTER. YOU MIGHT DAMAGE THE CPU.
The result is a drop from 80*C CPU at 55% fan speed to 72*C CPU at 26% fan speed.
I have replaced the soft eraser with a hard one after 2 months and noticed no difference between eraser types. This is the eraser after 5 months:
Note
If you want, you can take out the motherboard and replace the clock battery while you're in here. It uses the standard CR2032 button cell.