They run the same pins to you just swap the connector from the old fan onto the new fan. Theres no reason to touch any of the parts inside other than the fan.
It says on the review of that psu, that it's only when run over 600w load that it is loud, so you should check to see what your pc uses @ full load anyway as I doubt it will be pulling the full 600w with your current system.
It looks easy, just take the lid off, unscrew old fans, replace with quiet fans, put lid back on!
Got the psu on the mm at a good price, can't afford a 1000w silent psu.
Which fans would be best? One needs to be just 15mm deep.
To be fair, I doubt you need any 1000w PSU and if you do the noise from the rest of the system would probably be more of an issue
After the cost of the new fans (SilentX and Noctua aren't cheap) it might be easier to sell it and buy the 850W Corsair which should be a lot quieter, no voiding warranty and no risk of the PSU overheating.