Modifying a PSU fan

So I bought a ST45SF-G for my project and sent it back due to being to loud. Bought a fanless seasonic and it whines. Didn't really want it outside of the case anyway. So bought another ST45SF-G, with a view to modifying the fan to make it quieter.

My first thought was to space the case out 10mm and fit a 25mm thick fan as it'll only take a 15mm tall fan, but I'm already going to have to lower the psu in its position, so it'll literally be resting on the floor.

So my thoughts are to fit a better quality 15mm thick fan with a resistor so it'll always be quiet, and flip it round so it'll exhaust hot air out of the psu. Then another fan blowing air through the side of the psu, now what would be the most reliable way to control this fan? CPU or GPU temps? (3570k/7950)

Next question is what would be considered the quietest 15mm thick 80mm fan for this job? What value resistor should I put in the way? I'd still like it to be quiet on full load.

I have found this...

"What we know is that the ST45SF-G is designed to run the fan between 7V and 12V, directly proportional to load. At 7V the fan is spinning at 1800rpm, which is rated at 18dB@1m. At 12V the fan is spanning at 3000rpm, which is rated at 35dB@1m"

1800rpm on this fan is too loud, so I'd like it to be spinning at say 800-1000rpm at idle, and say 14-1800 on full chat.

While we're down there, could someone remind me what I should avoid touching when opening the psu case.

Cheers

Unplug the AC power cord (do not merely turn off the rear switch or the switch on the power strip or battery backup supply), then press the front panel power button to discharge the PSU's big high voltage capacitor faster than its bleeder resistor will do on its own. Lots of components inside the PSU have high voltage riding on them while running, possibly including some of the big heatsinks.

The average current drawn by a fan is roughly half the value shown on the label. You'll need a resistor rated about 10-50 ohms to slow the fan significantly and probably at least 1-2 watts so it doesn't get hot enough to melt the plastic insulation off wiring. Cover the resistor and its wiring joints with heatshrink (do not merely wrap with electrical tape), and keep them away from high voltage components. You can use a wirewound adjustable resistor (potentiometer) mounted through a hole in the PSU case instead of a fixed resistor, but whatever you select, be sure the voltage going to the fan is high enough to always make it start (probably 5V, minimum), and test when the PSU is stone cold and the room temperature is low -- I had some PSUs whose fans sometimes wouldn't start in rooms colder than 70F.

I'd rather look for a different fan because some are much quieter than others. Curved blades and lots of them are indications the fan was built for low noise.

Thanks for the reply. I've done some reading, and fortunately Silverstone listened to the complaining users and did a revision 2.0 where the fan speed has been modified to run at a lower RPM.

The fan is still of poor quality and gives of a bearing noise, so I have purchased a Noiseblocker BlackSilent Pro Fan PC-P to replace the stock fan. It is only on a mini 2 pin fan connector like a gpu, so an adaptor has been bought - no soldering and I have a bunch of spare fan speed resistors from various other fans. Should go easy hopefully.

Please make sure that everything inside the the psu still gets enough cooling. Otherwise you can expect a BANG.