This is an attempt to fix a fat PS3 with YLOD issue.
Better watch the PART 2, it's much better solution I did for IHS , no liquid metal, better.
   • PS3 fat delid like a Pro and fix YLOD...  
First cleaned and checked with the capacitor boost ( adding caps beside the Tokin ones) no success.
This means the caps are not at the origin of the YLOD failure.
Only thing left is to delid and enable the additional pressure on the silicon die to fix the 1st level interconnection. See the video to understand the flip BGA issues.
This is the only reason these units are failing with the YLOD because the heat affects the die connection to substrate.
If the IHS ( integrated heat spreader ) loses heat transfer efficiency, because of aged thermal paste between the die and IHS, then the high temperatures will affect the 1st level connection. It's not PCB delamination, it's not that hot to get things affected.

I believe almost everybody missed the 1st level potential problems. Magical hair dryer fix... :)
It may be a bad batch of epoxy that is expanding too much and brakes the connections.
Thus the necessity of pressing down directly on the die to compensate for the bad connection. This can only be done if you delid and remove all the mechanical support ( silicone or the white glue ) for the IHS, to rest directly on the die. This is basically what I have done with 3 units.

I do not have more fat PS3 to test but I am confident this is the way to restore those units.
I have played hours with the one i first fixed and still boots up every time and no freezing during the games. The other ones are still booting fine even if I keep them off.
Because of the liquid metal thermal compound the temperatures are very good.
You only need to have a thin film of that on the dye, no visible droplet.
Application on the IHS is not even needed, I could not spreadit because of surface being repellent, I just leftit almost untouched by any liquid metal compound. It works just fine only on the die.
After all is reassembled, I put the hair drier in the back and heat for about half hour. Hair drier is by far not capable of reflowing, remember is safe for your hair.
Heating up is also good to expand and release any air pockets in the Liquid metal and heats ink compound.
I did not fully wait for the warm PS3 to cool down, just power on repeatedly until there was no more overheating shutdown, it finally stayed ON !!!!
That's it folks, keep repairing these wonderful units if you find them.
Tools are from amazon, the excellent painting tools and the dollar store bubble liquid to make the tool slide like butter.
PS: I had to let yotube mute some parts where background radio was playing song. Good to know for the future.
Let's save the planet one item at a time!
PS: The other video I made with the 3 PS3 fat actually working in the same time is the "proof" this fix is worth trying.
Just checkit out.