There may be just a wee, rare outside chance (perhaps one in a million) that when you "wiggle" the card it improves on a dirty contact in the card slot; I wouldn't go as far as saying that cleaning the card slot with a toothbrush and forced air along with cleaning the card contacts with an eraser followed by wiping with alcohol would help, but after changing the power supply and completely recapping the motherboard, you might give it a try.
