80plus ratings are, however, ONLY an applicable metric IF the unit is already an otherwise known and high quality platform. Sometimes, not even then.
Take the EVGA B3 power supplies. Three of four tested failed Aris Mpitziopoulos testing. Aris does the PSU testing for Tom's Hardware and some other sites. He's also part of the Cybenetics labs project that tests power supplies on a variety of categories, and in ways nobody else does.
Those units were all a pass for Bronze 80plus, it's predecessors the B2 series generally managed Silver 80plus in testing even though they too were only technically Bronze units. Even so, all the B3 units EXCEPT for the B3 650w model failed testing or outright blew up.
80plus is only useful OR trustworthy if you already know the platform in use is good AND that it's being built by a trustworthy company, rather than being outsourced by that company to another company, that is not so trustworthy or even "known".
These B3 units for example, were supposed to be built by Superflower, somebody with a good track record of solid units in the Leadex, Leadex 2 and Golden green platforms that have been used on their own and most of the reliable EVGA models for years now. Instead, Super Flower outsourced the building of their platform to RSY instead of Super Flower, and they were not reliable. Then Super Flower pulled the manufacturing back in, supposedly, but after those tests, until I see newer tests to the contrary, I would not trust those models.
Then there are really solid models like the Antec VP-450, which has NO 80plus rating due to lacking active power factor correction and needing a switch to select power factor, which has historically been pretty solid. I know of at LEAST ten of these I've installed in systems more than five years ago which are still running fine today. Probably more.
This is what I think about 80plus as any kind of measuring tool against a unit being good or bad.
https://www.hardocp.com/article/2011/10/04/80_plus_irrelevant_to_you_when_buying_psu/#.VCs8dul0xhE
And this just makes using anything like 80plus, which is an unregulated standard, worthless.
https://www.hardwaresecrets.com/power-supplies-with-fake-80-plus-badges/