I have an ATI HD3450 in a Dell Optiplex 760 box. I tried the Sparkle GTS 250 1 GB, but it being a full size card did not fit. The heatsink on the fan hits the edge of the big plastic cover on/over the CPU heatsink. Whats my best option here? I'm looking to run a DC app(Folding@Home) and maybe play some games. I cant go with something thats too power hungry obviously, since the PS is rated at 300W.