Ritwick98 :
what if i get fx6300 with r9270 2gb ddr5
but clock speed of r9270 is 920MHz and requires 600 watt
whereas the gtx 750 ti is 1033MHz and requires just 400 watts
Here is Guru3D's power supply recommendation:
AMD R7 260X - On your average system the card requires you to have a 450 Watt power supply unit.
AMD R7 260X Crossfire - On your average system the cards require you to have a 650 Watt power supply unit as minimum.
AMD R9 270X - On your average system the card requires you to have a 500 Watt power supply unit.
AMD R9 270X Crossfire - On your average system the cards require you to have a 700 Watt power supply unit as minimum.
AMD R9 280X - On your average system the card requires you to have a 550 Watt power supply unit.
AMD R9 280X Crossfire - On your average system the cards require you to have a 750 Watt power supply unit as minimum.
I'd say r9 270 will work fine on 500w PSU Corsair 500W ATX12V
http://pcpartpicker.com/part/corsair-power-supply-cx500