*sigh* THERE IS NO SUCH THING AS PERMANENT!!!
But, if you want to 'get it running' for about a Week to 3 Months (Depending on Conditions), then
1 ) Remove ALL Thermal Paste,
2 ) Clean with Isopropyl Alcohol the GPU and CPU,
4 ) Apply Flux, to the side of the CPU and GPU BGA's (Ball Grid Align. This is where the Solder Crack(s) are),
5 ) Heat the Flux (EG: For 5 seconds) just to make the Flux flow
under the CPU and GPU BGA's while holding the board upright, until it comes out the other side. Now, place the MoBo (PCB) as flat as possible. Usually, it is a good idea to put it under something solid, and not something that will melt,
6 ) Heat Gun the CPU first, at 215 Degrees Celsius for 15 Seconds. Make sure, that you go in a 'square' motion and not in one place. Also, the PCB (MoBo) will make 'cracking' sounds. This is normal. It will also do it when it cools, so don't freak out!,
7 ) DO NOT TOUCH OR MOVE THE BOARD! ... Continue happily ...,
8 ) Heat Gun the GPU second, at 220 Degrees Celsius for 15 Seconds,
9 ) Let the board cool for 30 Minutes. DO NOT TOUCH, OR MOVE IT WHILE IT IS COOLING!
10 ) Test it by plugging the board in, and turning it on for 10 seconds max. Just so you can see that 'Green' light show for you
11 ) Assemble with FRESH
Arctic Silver 5 Thermal Paste (A nice thin layer. Just enough so it does not show the Metallic Chip) and the X-Clamp Mod (Screws / Bolts, Washers etc).
This also works for PS3 (of course), however - you can not do the test. You have to assemble it all the way to the PSU in order to test it. Also, bend the stock clamps slightly to add pressure to the Heatsinks that press against the C/GPU).