You run the risk of the GPU falling off the board if you try to reflow the solder with the ASIC pointed downwards.
However, looking at the PCB design, I can tell this is an NVIDIA card. Judging by the power connectors, a GTX 8800, maybe even a GTX 260 or 275. These cards are notorious for their failure rates after about 2-3 years, because the temperature fluctuations of regular use end up causing the solder connections on the bottom of the GPU to crack.
Baking these is totally viable:
http://tech.icrontic.com/articles/de...ven-mad-owner/