Hi guys, I am wondering what wattage i should go for in a PSU for my new setup:
i7 920 OC @ 4.01Ghz
MSI X58 PRO MB
OCZ 3x2G DDR3 10666 Platinum 7-7-7-20 @1600MHz
XFX HD5970 2G GDDR5 BE
OCZ 120G Vertex II E Series SSD
Seagate SATAII 1.5T 7200RPM HDD
Corsair H70 (both fans in use)
Antec 900 (3x 120mm + 1x 240mm fans)
Usually have around 5 usb devices in use (mouse,Kb,cans etc).
For a power supply, there are plenty of online power supply calculators where you enter your components and it adds up all the wattage requirements of each you enter. Using a calculator, you can add what you might want to have added in the future, such as a second video card, etc. I tend to add about 10% over that number for margin. It makes no sense to have a power supply way too big (cost goes up), and you certainly don't want a power supply to be too small.
Think of it this way, give a man a fish, he eats for a day, teach a man to fish, well, you get the idea.
(added in edit, when it came to me)
my setup is similar to yours and I had an 850W Corsair power supply. When I calculated what I needed, including a second graphics card, and taking into account the overclocking I am doing; the calcuators I used gave me 820watts that I needed. Understand, too, that is maximum power you need; most of the time a computer as you use it is only idling along using less than half that value.