I currently own an Radeon HD 5570 graphics card which "supposedly" consumes a very small amount of power. The problem is that it stutters during some games and movies. My machine is an Intel quad core i5 - 750 with 4 gig ram running on windows 7 using a 550w Antec Basiq PSU.
I plan to upgrade to the Nvidia GTS 250 card which requires a 450w minimum PSU.
Would I see any substation cost difference in my monthly electricity bill? I mostly just use my computer for browsing the web, programming and watching movies. 5%-10% of the time I might spend playing games.
I reside in NYC, according to: http://michaelbluejay.com/electricity/cost.html my kilowatt per hour is 14¢.