my PC is made up of a AMD phenom 9550 ,two sata harddrives, a firewire PCi card , a creative extreme music sound card and a diamond 3650 graphics card . I also have 2 sticks of DDR2 ram 4gigs total . My power supply is a sparkle atx 400pn . I am looking at upgrading my video card but am confused at the specs . according to the diamond site my current card only requires a 250 watt power supply but to step up to a 4650 it would require a 400 watt power supply and anything above that requires a 450 watt supply looking at the specs though it would appear that the 4600 series cards consume less power than my 3650 ? If I enter all my components into an online Power supply calculator though it shows that I should be able to run even a 4870 card with room to spare ? Also when I compare the 3650 to the 4650 the the 3650 has a higher clock speed and it also has a higher memory band width rating 80 gigs per second as compared to 8 gigs per second . Will I notice much difference between the 3650 and the 4650 ?