I need help with my graphics card...

One of the screw holes to hold my GPU in has stripped and no longer tightens. Now when my GPU fans increase in speed, the case rattles with vibration. What can I do to fix this problem? I was told that I could use a bigger screw, but I'm not sure what type of screw I should buy.

if the hole on the chassis is stripped where the pci bracket mounts, you may want to try and find a self tapping screw that will fit.

As far as I know one screw is enough to hold a GPU tight enough so it won't move.