Spoke too soon. Fucking thing YLOD'd again after 2 hours. Buying a slim - I'm done :lol
Hope the following helps out another person who was as frustrated as me after two failures.. Here's what I did differently my third try:
1. Reflowed with heatgun at 650F for approximately 30 seconds each of the 4 areas on the non-cpu side. Let the board cool for 20+ minutes, then flip over to CPU side.
Here, I heated the entire board up just a bit. Nice and smooth movements with the heat gun around the entire board for maybe 30 seconds. Then I went in for the GPU and CPU ONLY. Did not bother with the 4 little panels below the BGAs.
Intense 650F heat, ~1inch away for 45 seconds each BGA. After 1 cycle on the GPU and CPU, I repeated for 15 seconds each @ 650F. Then I turned the heat down to 450F and began to slowly move the gun away as I continued heat gun movement for another 15 seconds. Therefore, rather than going from hot to cold right away, I let the board cool down gradually by keeping some heat on it. Then, let the board cool for 20+ minutes again, and that did the trick!!!
2. Thermal paste was a big issue of mine. I used Arctic MX-3. The best way to describe my method is a 'liberal line of paste'. I tried a thin line in attempt #1, and I could actually read 'RSX' on my GPU... Too thin!
Attempt #2 - Thin line again, followed by extra bits as I deemed necessary. Ended up a mess, and when I pulled apart the PS3 a third time, my work was obviously poor.
Attempt #3 - I decided to study Gilksy's video again. Watching closely to try to gauge how much he used, I decided to move from a thin line to a thick line. I ended up using 1/4 of my 4g tube on BOTH the GPU and CPU. Therefore, I used approximately 0.5g of thermal compound on the GPU, and another 0.5g on the CPU.
Left a nice paste layer - kind of like thin birthday cake frosting, if you will. I couldn't read any of the writing on either of the BGAs.