Pc sticking on games.

Question

I recently installed a new graphics card.i had the same sticking before,but cooling the system down with fans ect,fixed the problem,now with the new graphics card...its doing the same.do i need to increase my cooling.i have heatsinks on the ram. and a geforce 9600 gt nvidia graphics card.and a 3ghz duel core processor.2gigs ram.processor temp at idle is +- 54 degrees and ram is around 35-38 degrees.i have one exhaust fan at the rear and 2x small fans blowinfg on the ram.