sagmani :
Do you thing I would need the 750w for this spec, assuming not using it in the future for future upgrades, wouldn't a 650w be enough for this spec?
Yes, if you don't think you will upgrade in the future, your build will only pull about 350-400W MAX so even a 450W would work. If you want to save some extra money you could go with a 550W but 650W the best choice as it'll run the system at it's peak efficiency.