Nice Marmot wrote:
Would a 520W always draw more power and produce more heat than a 430W, even at the same load? If not, the HX520 looks real nice: not crazy expensive, modular cables, quiet, and fairly future-proof (for 'mainstream' systems).
It depends on the individual PSUs' efficiency curves and the power demand of your system. If your system mostly draws <100W, then a similarly high efficiency but lower max power PSU will generally give you lower real power usage. Such as, for example, the Seasonic SS-300SFD
, which is >80% even as low as 40W load. But not the Seasonic S12-330, which has an efficiency curve much like the Corsair, not reaching 80% efficiency till close to 150W
For what this means in real world terms (watts, not percentages), let's assume 70W as idle power draw -- fairly typical for a modern system with a decent but not major gaming card.
Enermax EG701AX -- ~72% eff -- 97W
Corsair 520 -- ~75% eff -- 93W
S12-330 -- ~75% eff -- 93W
FSP Zen -- ~81% eff -- 86W
SS-300SFD -- ~84% eff -- 83W
PicoPSU -- ~85% -- 82W
The Enermax is not high eff by today's standards, hitting a peak of only ~78.5%. The last two have the best low power efficiency of all PSUs tested.
The worst and best eff. (at 70W) are 72% vs 85%. It looks really significant, yet the actual power difference is just 15W. Swapping a 60W incandescent with a 15~17W high efficiency bulb will save you a lot more energy with much less expense and trouble.
That assumes your PC will be at idle most of the time. Mine is. I know from monitoring my system AC over the years (now that I no longer do any distributed computing).
My take on all this is....
1) If you can match the PSU to your system needs, and get a PSU that's high efficiency in the range where your system draws most of the time, go for it.
2) Still, make sure you have at least 25% headroom beyond the maximum power draw of the system
3) Don't go crazy trying to get the highest efficiency -- consider the real WATTS, not just the percentage.
One idea I have is to request a special SPCR variant of the SS300SFD 80+from Seasonic:
1) same quiet 80mm fan used in Antec NeoHE
2) longer sheathed cables, perhaps a couple more than is supplied, and one 6-pin PCIe power plug & a 20/24-pin ATX plug
3) ATX mounting adapter included
Alternatively, the SS300SFD 80+ circuitry in a standard S12 casing...