I have a 240V PSU. I opened my Pre-built PC up and it says that it is +12v -12v 0.3 and that is all i can remember. It also had 85W and 200W written on it. I want to upgrade my NVIDIA Geforce GT 620 1GB to Geforce Gt 750ti. I have an amd a10 6700 6gb ddr3 ram. Help? Im not to knowledgable on power supplys!