I have faced with that problem many times in last 2-3 years. I've tried many things that almost all the written in that site. No any hardware soldered or replaced since that problem started. But only the BATTERY was replaced. I noticed that this problem was disappeared when battery was new but after 1-2 years it come back again. Then suddenly i decided to unplug the BATTERY and powered-on the system and it fixed. I think ,There is voltage level or fluctuation problem occuring on the mainboard(or around the graphic card side) when the OLD BATTERY is plugged. Now i'm using laptop without battery and without any problem!!!!!
Please try and share result with us. Thanx
Tero