A quick solution for my card:

When I installed the HR-03 GTX and all of the various Enzotech sinks, and the dual Skythe 120mm fans, needless to say, there was some warping of the pcb.
I cut an old cathode ray tube (the blue tube under the far right side of the card in the photo) to size, and put some plastic washers on it for insulation and fine adjustments. Then I put a bolt with plastic washers on it through an open hole in the back front corner of the card, and rested it on the tube. The bottom of the tube is held to the base of the case with the velcro pad it came with.
This straightened the card nicely and adds enough support, but is still easily moved for card removal.