Hey everybody, and I hope each of you are having a nice weekend.
Right now I'm running an Antec EA650 (650W) on an upgraded Dell E520 system. It was sort of an impulse buy at Best Buy three years back and I'm wondering if I should switch out the power supply to gain a bit more efficiency for my system.
CPU: Stock Intel Core 2 Q6700
RAM: 4GB DDR2 PC6400 (mixed brands)
Mobo: Standard Dell BTX P965/G965
Graphics: Asus Radeon EAH4870
Although I'm a big fan of efficiency myself, in your case you'd be spending a lot of money for very small savings that probably would take years to pay back. You would save more by getting a different graphics card. A GTX460 is more powerful, but uses less power at idle, where your PC spends a lot of its time.
Upgrading a power supply just for efficiency is just going to cost you more money than you will save, especially coming from a unit thats already 80+ basic certified, even if its only 80% at your systems max load and the Seasonic X series would be 90%, you probably only pull 400W max underload so you are talking 40W and how, its going to take a longggg time to make up for the investment in power savings.
As jtt283 said, one of the GPUs from the last two generations would actually add up to more, the 5xxx and 6xxx series have vastly improved power saving features over the 4xxx series so you would drop your idle power quite a bit which would add up just as fast, but actually give you some extra performance in the process.