Copying this from r/buildmepac
This will cover common myths and misconceptions about PSU's. It is a long but worth while read ahead if you don't have a good understanding of PSU's.
I will break this up into sections this is a LOT of text and I want to it be readable. This is 8 pages or so long in Microsoft word if that gives you a idea and between this and everything in the links probably pushing 70 pages or so worth of material.
I see people are recommending Evga BR's, Evga GD's, etc which all lack reviews. How can you recommend something if you don't know about its performance or build quality? It would be equivalent to recommending a GPU without looking at benchmarks or reviews for it. I give people a pass to do in on ~$250 budget builds since it is expected corners to be cut but I see this with budgets such as $500 when you can easily fit in a good PSU choice.
"What do you mean by lack reviews? They have tons of amazon, etc" or " I have it and works fine so it must be good"
Consumers can not review PSU's. They are one of the very few parts that consumer input is generally worthless on since there is no easy way to test it unlike a CPU, GPU, case, etc. Consumers just can't simply review a PSU since it requires opening it up and taking it apart, extensive knowledge about electrical engineering and PSU's, and having expensive equipment to test performance. The first two are doable but the 3rd is what really stops people. Most people don’t even own a simple oscilloscope much less everything a place like Tom's uses. Its why most sites and channels either half ass PSU reviews at best or don't do them at all. The reviews that matter are professional reviews from sites like Tomshardware, Techpowerup, Jonnyguru, etc.
http://www.hardwaresecrets.com/why-99-percent-of-power-supply-reviews-are-wrong/
This is more geared towards websites but it applies to consumer reviews too.
This is everything Tomshardware does to review a PSU.
http://www.tomshardware.com/reviews/how-we-test-psu,4042.html#p1
My go to site is either Tomshardware or Techpowerup since they do very in depth testing and are really the only sites that I know that test out protections.
Another common one I see is " its gold or bronze rated so it has to be good".
Definitely not true. Efficiency is just that. Efficiency. It does not equal build quality or performance and is no way reflective of how good or bad a PSU is. Yes if a PSU lacks 80+ rating it is a bad sign since it either means that it is using some awful platform or the company is so poor that they can't even pay the ~$1500 required for 80+ to test the PSU but if a PSU has a 80+ rating you really can't judge how good or bad it is by it. Also the 80+ rating actually isn't good for showing efficiency since the testing is done at room temperature which isn't realistic and units can be under rated such as the Corsair CX which some models are actually sliver rated and some do nearly gold. Plus, when it comes to saving money outside of extremes you are looking at a few dollars saved a year, it could take years or even decades to make up the cost of a more expensive unit with higher efficiency. More on that below.
Another very common one I see is "Gold is better than bronze because it saves you a ton of money".
No it does not. Outside of extremes efficiency is pretty pointless.
Lets assume we have a PC that needs 300W, pretty typical for a gaming PC.
https://en.wikipedia.org/wiki/80_Plus
For the sake of simplicity let’s say we are going with 90% efficiency for gold and 85% efficiency for bronze. It is 330W that will be pulled from the wall for the gold rated PSU and 345W for the bronze rated PSU. The difference is only 15W. I think you can see where this is going.
https://www.rapidtables.com/calc/electric/energy-cost-calculator.html
Using a energy cost calculator lets say the kWh cost is $0.12 which is a bit high in my experience (I think mine is like .04) and lets say it is at full load for 6 hours a day. That is a difference of $3.942 per year at $0.12/kWh and a measly $1.314 per year at $0.04/kWh. That is correct. You can run the numbers yourself. This is why I said it is pointless to consider outside of extremes e.x rendering farm, a huge server, 80 plus vs. titanium etc.
A 450W CX is $60 and is "bronze rated" although it does sliver and nearly gold in reality, another reason efficiency is pointless, but anyways for the gold rated 450W PSU a BitFenix Formula Gold at $75.
With a $15 difference at $0.12/kWh with the conditions stated above it would take almost 4 years to break even on that $15 and at $0.04/kWh it would take a bit over a decade.
Why do manufacturers push for efficiency so hard if it really does not save much money? Because unfortunately the mainstream consumer i.e not a enthusiast believes that efficiency is a sign of quality or performance. It is how Evga G1 managed to sell for years despite being a low-end PSU due to group regulation and is also what their current business model seems centered around but that is a discussion for another topic.
One that is almost common as oxygen in the air is "X brand is good so it must be a good PSU".
Brand is generally meaningless. Yes, companies such as Logsyis and Diablotek solely produce fire bombs but they are the exception to the rule. Most companies will have high end units, low end units, and stuff in between. Going by brand will not ensure you get good unit. Seasonic has the turd that is known as the M12II/S12II. Evga has quite a few such as N1, B1, G1, W1, and BT to name a few. Corsair has the VS and CV. Etc. I think you get the point here.