replace logic board with core duo?

there seems to be two different logic boards shown for the intel 17" - the 1.8GHz, if you look at the last pics to replace LB for both the isight and 1.8 intel they look identical down to the screw holes. Anyway, I am getting an error from AHT - ATI/1/4:113-xxxxx-113 - the video ram, right? I already replaced all the caps and nothing has changed - I suppose it is possible that I had a bad cap and then have a dry solder joint, but I think that would be a strange coincidence. Before I trash this board, i am going to try and put a heat gun to the video RAM, maybe I can remelt the joints and get it working...

I was reading another post about the video graphics processor going bad and displaying a checker board. This is exactly what my iMac is doing - you said you had fixed these before - can you explain how to do it ?

yes i did this job on about 30 iMacs. it's a little bit hard to explain - is use different tools do do that. here is a video of someone fixing the ps3 YLOD with a regular heat gun - the procedure on the iMac board is the same - i think you will find the gpu.

Thanks, I took a look under the video heat sink and noticed a huge amount of extra compound, some touching the surface mounted pieces - after cleaning it up, the display was perfect. Two minutes later the power died on the logic board, so now I have another problem to figure out...