Mine does too, it doesn't help. It helps with the bowing, but not the sag. Reference cards have that heat plate that covers almost the whole card which prevents any bend at all and also keeps the card straight. None of these cards with aftermarket cooling have something like this and so pretty much all wind up with the same problem. Although the Windforce cards are dual slot, they have a much heavier heatsink than even the DCU2 dual slot cards and suffer great bow and sag due to this.
Another factor that helps in the process of bending is heat. He overclocked his card from day one which caused the board to heat up and weaken from the heat. Not all cards require overclocking and large amounts of heat to do this though.