i have bought nvidia 640 gt 1 gb ddr5 and i had 4 gb ddr3 ram. will it be compatible? and also i have intex smart it 2045 s+ psu of 450w my motherboard is intel dh55tc
absolutely yes. GPU and RAM are different, your motherboard should support your GPU, mostly your Power supply unit should be able to provide required power on your GPU and Mobo.