The PSU's two 80mm fans typically run at around 1600rpm in my system, which may give you an idea on the noise they generate.
Hey guys, it really isn't hard to estimate fan noise from basic info.
If you have 2 fans instead of one, add 3 dB. Add a couple more due to the fact that there will be double the turbulence effects from the airflow of 2 fans in a PSU.
Now, you say 1600 rpm. That's really useful info. The Panaflo, which has excellent bearings and is pretty quiet at 1900, puts out 21 dBA -- in free air. In a PSU at 12V, it will probably measure 10 dBA more. Call it 30 dBA.
These Thermaltake fans, let's assume that at 1600 rpm they are equal to the Panaflo. Call them 20 dBA. But there are two, so it's 23 dBA. Put them in a PSU, 33 dBA. Add a few more dB for the extra turbulence of 2 fans. I get 35 dBA.
My guess is that they are a bit louder than the Antec 2-fan TruePower PSUs. In the same ballpark anyway.
The best you can do noise-wise with a 2 fan PSU if you want/need 2 fans is to replace both fans with Panaflos or similar. If the PSU has the right kind of thermal control circuit, the Panaflos will be running at whisper levels most of the time, but kick up to full tilt for decent cooling at peak power. That would actually be a viable PSU for hardcore silencers.