I overbuy power supplies because I think, but have not tested, that it will convince them to run the fan at lower speed. This strategy has resulted in quiet, for sure, but I'm not sure that it gets you reliability.
This theory is sound. High-end power supplies tend to not turn on the fan until reaching 30-50% of their rated maximum output. Fanless power supplies are usually internally using the same components as regular high-end models with 80-100% higher output ratings, but with larger heatsinks. A high-quality oversized power supply with a fan will be silent most of the time, but keep itself cool when necessary.
( I have a semi-passive 750W power supply that has spun up its fan exactly once, when I accidentally shorted two of its power rails together and melted some wires while burning out the PCIe slot I was measuring the power draw through. The motherboard and wires had to be replaced, but the CPU, PSU and PCIe card were all fine.)
Spending days trying to chase down an intermittent reboot just to find that your 750W PSU is actually shitting the bed around ~350W is a terribly unsatisfying journey.
These days I don't know if that's entirely true, so I would at least look at reviews to make sure.
Anecdotally, Corsair has always been a top-notch company to me. Even when their products go bad, their support is awesome. I had a set of memory sticks appear to go bad, but I couldn't tell if it was my northbridge or the RAM itself. I was a cash-strapped kid, so I didn't have another machine to test with. Corsair sent out a set of known-good RAM sticks for me to test with, at completely no charge to me. When the test revealed that it was indeed the RAM that was going bad, they offered to let me keep the test sticks they sent me until my replacement came in the mail.
The OEM for most of their PSUs is CWT, but they are "Corsair custom" designs instead of off-the-shelf. Seasonic is only used for relatively few of Corsair's models.
Only one out of ~ 10 I bought ever failed on me, and that was after 2 years of no usage.
Jonnyguru's last Seasonic review: https://www.jonnyguru.com/blog/2018/07/03/seasonic-prime-ult...
Literally nothing in the bad & mediocre summary sections, and with nothing but recommendations for the entire series:
> Our look at the PRIME Ultra Titanium series has now at last come to a conclusion. We can now definitively say there’s not a bad performer in the bunch, and while all do have some very minor drawbacks I can’t see any reason not to recommend any of them.