Hi
If you think the Video Card is the problem and you are using the latest driver, try rolling back to the previous driver and see it that helps, it may be that when you reinstalled, it updated to a newer driver then you were using before.
You can do that in Device Manager just look at the driver and select rollback driver.
Or you can look for an earlier version online.
If you aren't using the latest driver try updating.
I just had a similar problem with the previous nVidia driver 13.something.
I had to go back to the one before that to get it to work.
Now the have released a newer one 14.07 and it works fine.
If you video card is overheating take it out and clean it and see if the temp stays lower, and check your vents etc. to...