guitarology, first you will have to remember that there are a few things that can cause the YLOD. A few of them are:
A dead or disconnected HDD
Cold-Joint between the CPU/RSX/EE(If your console has one)
A dead power supply
Corrupted NAND Flash
Even reflows are only limited. YLOD (as well as RROD on a Xbox) are caused by the design of the processor, not by bad or cracked solder joints. You most likely have issues with your GPU processor. It is a flip chip design and the issue could be the solder bumps between the IC and the substrate. A reflow might fix it for a while.Even reflows are only limited. YLOD (as well as RROD on a Xbox) are caused by the design of the processor, not necessarily by bad or cracked solder joints. The only repair that would fix it permanently is a new BGA. Try this repair again and you may have to change the approach a bit by adjusting the heat. It is a hot or miss situation and most first time failure with this is caused by not applying to much heat, whereas to much will totally remove the IC's.