I do tech support and was asked how I got to know so much by one of our clients. By messing around at home! So I decided to build a system mostly from the ground up, keeping my drives and PSU (although not mandatory). I decided to keep my SeaSonic S12 II SS-330 in my current build and have a good place to start with a ST30NF or a Corsair HX520 that I already own. I will have a third option, the one that will come with my Inwin case, but... nuh.
I won't use the ST30NF because the rest of my system won't be up for it. My CPU and my GPU will both be fanless. From previous experience, one fan can work but it has to spin above a threshold in order to keep the system cool enough and it becomes too loud there (~800 RPM for Scythe S-Flex D that I'm using as a case fan).
I was using the Corsair before but hated the fan. Really annoying! I was looking forward to experimenting with a fan swap. Here are the fans I have and the reason why I am or am not using it. The only power to the PSU is an Antec tester, so not much. I have the PSU open, connected a fan, put it on top and turned the power on with the tester. I then picked up the fan and tried to stop it, listen to it, etc.
1. Yate Loon D12SL-12.
Spins up right away. Spins back if I stop the fan manually. VERY quiet. This fan belongs in the Hall of Fame of 120mm fans IMO. Won't use it because I want my fan to use more exotic bearings than sleeve bearings. I've read somewhere around here that sleeve bearings might get noisy after about a year of constant use. I have become a fan bearing snob!
2. Scythe SY1225SL12M & SY1225SL12H Slipstream
The H does not spin up and will stop almost right away if I nudge it to spin up. A few days ago I had it in a semi-complete system with the HX520 and it spun up by itself sometimes but the PSU got pretty warm, although not hot.
The M will spin and will spin back up if I stop it manually. Very quiet, quieter than the Yate Loon, but probably blows less air, too (I honestly didn't listen that carefully). Nice.
Won't use the H because it won't spin up and even if it did, I probably wouldn't use it because, like the M it has sleeve bearings.
3. Noctua NF-S12-1200
Blows the most air out of all the fans here and is the loudest but it is not loud. It will spin right away and will if I stop it, too. Has the most torque. From about two or three feet it is almost inaudible but from just a few inches it makes many different noises depending on what angle you listen.
Won't use it because this fan makes a grinding noise when it is blowing up. If my PSU were upside down, this would be my fan!
4. Enermax Marathon Enlobal Bearing
Does not spin up but will stay spinning if I get it going. Barely spins, barely blows any air.
Won't use it because: it doesn't spin.
5. Scythe S-Flex SFF21F
Spins very slowly thus is very quiet and barely blows any air but does spin back up even if I stop it manually. Actually, a couple of times (I turned the PSU off, then on, then off...) it didn't spin back up but I would like to think that it would have if the PSU got much warmer. This is the fan I am going to use. If it doesn't work out, I got others or I still have a few bucks to try another fan.
I am very aware that my testing conditions are not at all like a fully operational system. I am assuming that the fan will always spin up when in my system and be very quiet but will ramp up when needed. I doubt my system will be even 300 Watts.
6. Not pictured: The Adda that came with the PSU.
Won't use because it sucks, it's loud. I think it's defective and Corsair gave me an RMA but I decided to experiment with a fan swap instead. I like that it's modular, efficient and has more than enough power for my needs.
There are also two fans in the picture that I won't use in the PSU: a Scythe DFS122512L-PWM and an Arctic Cooling PWM fan that I intend to experiment with as case fans connected to the CPU fan header on my motherboard.
I will start a differrent thread when I get the entire system up and running.