PSU advice

[aaronjunited]

For that system a single exhaust fan at the rear and 2 front intake fans would be fine. If you want 4 fans (i.e 2 front and 2 rear) then just run the exhaust at a lower rpm for positive air pressure, or if they are 120mm rear vs 140mm front then that should be fine for pos air pressure. I wouldn't bother with a bottom fan.

Older article explaining pos vs neg air pressure:

https://www.neweggbusiness.com/smartbuyer/over-easy/pc-cooling-how-to-set-up-computer-case-fans/

Thanks dude. Explains it for me.