I have a PS3 FAT 40 Gb that made a lot of noise - a real vacuum cleaner SO, I decided to make a FAN controller that was able to limit the maximum speed to a % of the "vacuum level". Even being a not so smart decision, I've made-it !
When I was doing some final tests I've short-circuited the ps3 fan control chip outputs and bricked (RLOD) the console.
In opposite to a "normal" RLOD, the fan never spins. The console turns on and off in silence. That's why I think it is really the fan controller. I've read some of the schematics of the 40G. Validated some fuses and even one of the zeners.