hello,
I have a machine imac A1312 with no display first gpu mxm card no 109-B97157-00 and bga amd chip 216-0769010.I changed the bga amd chip and now i get distorted video.I have put another card into machine works fine so there is surely gpu card problem.Please can anyone guide me what the problem is.

Is your 216-0769010 "new" or "like new":))) would you replace it by another??

well it say new but i think it was reballed i have a another chip 216-0769023 i put that an dthere was no video so i guess i need to change video bios.

I hope you checked all power voltages at mxm first..

yes i have checked all power at mxm but if i put another gpu card i get good graphics and the machine works.

"if i put another gpu card i get good graphics and the machine works "
if it 109-B97157-00 too try to swap bios then swap chips..

memory strap resistor on the 0 ohms missing.now works no distortion