Sorry guys. I was upgrade a desktop few months ago.Now i have an ASUS motherboard P7H55,CPU i5-760 2.8 GHZ,RAM 4GB,GRAFHIC CARD MSI NVIDIA 768GHZ,2 HDD MAXTOR 160GB,WD 750GB,LG OPTICAL DRIVE and sometimes i load an external hard drive touro mobile pro 750 gb how many watts do i need?corsair 620watt or something more