QUOTE(Weirdjerz3y @ Feb 24 2010, 03:59 AM)

Well, im going to try, if not , then i dont no,
Anyone can tell me the most common cause, like where is it usally located?
My bet is on GPU area. Heatgun it underside of the board as well and use little more heat this time, I think you didnt manage good reflow on your chip. Keep the heat at 550F little more than before. Also using no-clean liquid flux under the GPU chip, to wash up its solders, would help to do smoother and better reflow of these solders.
QUOTE(Weirdjerz3y @ Feb 25 2010, 12:55 AM)

Omg, thanks man, ill try it as soon as i can.
Where exactly or how do i apply the no-clean liquid flux?
There is a small space between the GPU chip and the mainboard (you can see the solder balls if you look at the side). You will make the liquid flux go thru this space and exit at the other side of the chip. make sure it goes everywhere under the chip. Then clean the around area that got "wet" as well and wait 5 minutes, the flux to vaporate and leave the flux on the solders to reflow. Then do your trick with the heatgun. I hope it works.
P.S. be sure you have no-clean liquid flux.