The thermal paste in the PS3 *is* liquid already (at least what's between the heat spreader and the heat sink), it doesn't melt, it's never solid. Separation from the heat sink9s) would be due to the board warping, but it would also be very hard for this to actually happen simply because of the way that the console is set up. I've got to tell you that unless you know for a fact that your PS3 is being reballed professionally, that you're probably just getting ripped off when you send it or take it somewhere for a repair (someone's probably just stripping it down, blasting it with a heat gun, then putting it back together - it may make the console work for some time, but in fact it's not being fixed). The heat spreader needs to be removed, then the RSX chip (most of the time) needs to be removed and reballed, then reflowed onto the motherboard. There are many potential problems with the PS3, and the YLOD/beeping/red light don't give any secondary error codes like the Xbox 360, so repairs (or attempts) are usually hit or miss. I've "fixed" a few of them with a heat gun myself, and I've replaced a few Blu Ray drives as well. I wouldn't pay anyone to fix it unless they showed me their machinery first.