Meanwell Power Supplies Efficiency isn't associated with load in that manner and does now no longer parent in what number of watts you want in your machine see edit on the bottom, I misinterpret your question. Getting a Power Supply Unit with extra watts than you want is to get longer existence from the PSU. When you push a PSU hard (i.e. power it close to its most output) it's going to burn out quicker. Burn out the capacitors derate over time, with use, and with heat. This makes them much less capacitive, lowering the strength of the PSU. A precise nice PSU while new might be capable of delivering a piece extra contemporary than its rating. But with use, someday later its max strength output will drop underneath its rated max. If you haven`t left any headroom and want nearly all that strength, that PSU isn't always going to close very lots longer. i.e. the closer its max output it's miles driven to, the quicker it's going to put on out. As its max output drops, the desired strength does not so it always receives driven tougher and tougher. Also, you may improve to extra effective hardware inside the destiny which in any other case wishes a PSU could change. I continually purchase a PSU with at least 1/three more strength headroom. If I want 550W I'll purchase a 750W. This proved practical closing 12 months after I sold a 3090 gfx card and happily already had sufficient strength to power it without changing the Meanwell Power Supplies regardless of it already being nine yrs.’ old. Efficiency best influences how lots of strength is drawn from the wall socket for the quantity of strength your PC is using. The extra green its miles the much less more strength is pulled from the wall via way of means of the PSU for its inner operation. And additionally commonly reduces how warm the PSU receives. Efficiency will range from low watts to excessive watts, peaking someplace inside the middle. It does not typically range that lots except you operate little or no strength or close to max strength. This has not had anything to do with how lots strength your PC wishes, the PSU strength provided to the PC is unbiased of its performance. The best time performance which could assist with a strong draw problem (apart from the price of strength) is in case your PC is so effective, its PSU is maxing out a wall socket's contemporary capability. Then an extra green PSU can probably maintain you in the wall delivery constraint. Although undergo in mind, performance will lessen a bit the warmer the PSU receives and additionally with age/use. It can pay to maintain your PSU cool to apply a bit less strength and close longer. I reread your question, top performance does not range that lots over the strength variety to count except you push the PSU hard. Also, in case you insist on staying in the top performance zone, you may want to maintain your PC jogging hard, eating extra power anyway, and defeating the objective. If you're involved in approximate performance, get an exceptionally green PSU with a piece of strength headroom defined above, and contact it a day, you are not doing better.