Posted by Sir Four at 11:12am Jan 6 '12The one I built a few months ago. I haven't measured it under load yet, but it idled at 54W. I think that's pretty good. Then I had the occasion to test the wattage with a different PSU. The PSU I had in it was an already-thrifty 400W rated 80-Plus Bronze, which means it should run quite efficiently. I swapped it out for an Antec 380W 80-Plus Bronze "Earth Watts" PSU, and measured again...all other things remaining unchanged. With the Antec, the comp now idles at 50W.
Of course, a difference of 4W is not that significant. But it is a measurable difference. This demonstrates the fact that different PSUs really do have an effect on your comp's power consumption, and if you want to build a comp that runs as efficiently as possible, your PSU choice matters. I expect there would've been a more significant difference had my first PSU not already been an efficient model.
As a general rule, you want your PSU to be power-rated appropriately for your computer's actual needs. If you put a 750W PSU on a computer that draws, say, 80W, you are quite outside the PSU's "sweet spot" of efficiency. You really want to aim for a PSU rated low enough that your computer is typically drawing 20% or more of the PSU's wattage rating. In my case, a sub-300W PSU would actually be ideal, and would yield the best efficiency. It's a shame they don't make many good PSUs in that range.
Of course, a difference of 4W is not that significant. But it is a measurable difference. This demonstrates the fact that different PSUs really do have an effect on your comp's power consumption, and if you want to build a comp that runs as efficiently as possible, your PSU choice matters. I expect there would've been a more significant difference had my first PSU not already been an efficient model.
As a general rule, you want your PSU to be power-rated appropriately for your computer's actual needs. If you put a 750W PSU on a computer that draws, say, 80W, you are quite outside the PSU's "sweet spot" of efficiency. You really want to aim for a PSU rated low enough that your computer is typically drawing 20% or more of the PSU's wattage rating. In my case, a sub-300W PSU would actually be ideal, and would yield the best efficiency. It's a shame they don't make many good PSUs in that range.