1. https://en.wikipedia.org/wiki/80_Plus#Efficiency_level_certi...

2. https://www.jonnyguru.com/blog/2015/10/25/corsair-rm1000x-10...

I usually drop a 750 watt 80+ Gold into most of my builds, even though a 500 watt or even a 450 watt would be sufficient with a single GPU, and have no plans for a second GPU.

Efficiency usually starts tapering off below 50% and below 30% it falls off a cliff - however, that just means instead of an ideal 10W power consumption you're actually pulling 30W or something like that, it is usually not a big deal in absolute terms.

(there are also some exceptions, some of the platium/titanium PSUs actually can hold pretty decent efficiencies right down into the basement.)

750W is a good "standard" recommendation, that's enough for any one GPU on the market.

The rule of thumb is really more to guide people not to buy 1600W or 2000W monster PSUs just because "bigger number is better!".

(Although those giant PSUs do have the advantage that they can often run completely passively under load, they won't kick fans on until 50% or 60% load, which for a 1600W PSU means you can comfortably run a high-end GPU and a high-end CPU completely passively.)

No, you're not wrong. Not sure how what I wrote conflicts with that. I don't think it does.

That's what tripped me up, I think. Even without a second GPU, 80+ Gold or better is a good choice.

Your next sentence makes sense though, 1KW PSU's are usually overkill, even if you like to oversize your PSU like I do.

The selection was "gold", specifically. And that's not as bad as it might be, but titanium is better across the board and much better at low load. A titanium supply is more efficient at 20% load than a gold supply at 50%, for instance.

If you're over-sizing your power supply by ~60% (as is the case here) then this is significant.

But, you build enough "rigs", you learn not to skimp on certain components like PSU's, Cases and Motherboards... which is normally where new builders cut corners.