I am getting one for my server which is a AMD X3 PI and a MB with onboard Nvidia 8200 gfx on, so max load should be pretty low. Just wonder if it will be as quiet as my HX620 (With same load %)

Hi, I recently purchased one, thinking it might have a hint of the HX620 I have in another machine.
Unfortunately there is a reason for it's price. It has very loud noise. You can hear every rotation clearly. This is also put in a machine that draws little watt.
Do avoid the same mistake I did. Pick one from the recommended list here.

I have the 400W, and it's decently quiet, however, it ended up being the loudest thing in my system. My Arctic Cooling 64 Pro at 1000rpm I can't hear even with every other noise generating thing in my system turned off, and my hard drive, well, it's loud, but I can't explain it, it makes a different kind of noise as compared to the PSU, so I can hear both at the same time. It's weird.

It's quiet, but for me, not quiet enough, I just ordered a replacement Scythe fan and will be replacing the ADDA fan. I guess to really answer your question....how loud is your machine right now? I have a very quiet PC, so this thing ended up being the most audible thing in my system, but it is still decently quiet. So if your machine is somewhat audible, then this PSU you probably won't be able to hear, but if you have a SUPER SILENT system, then you'll hear it.

I hope that answers your question (but it probably just confused you more!)

From my point of view it is louder than the Enermax Liberty 500 I had in the previous build.
At idle, shouldn't be much difference between the Corsair power supplies, because they use similar fans (all are produced by ADDA, different speeds). And, especially this one, shouldn't be loud at idle/low power systems, because it is a low rpm fan. I find it odd that there is such a big difference between CX400 and HX620 in terms of sound.

In other words, it's my loudest piece, I can hear it, at night, from about 4m away, and this without any load.

The best PS, in terms of sound, I came in contact with, was a "no name" one (Green Power or something), equipped with a Yate Loon , 120mm, low rpm fan. If I remember well, I barely could have hear it from a close distance (10-20 cm); to be more specific, a 12 cm Nexus Real Silent Fan was louder.

The future should be a high efficient PS equipped with a low rpm 14cm fan and heat pipes (like Zalman has) in addition to the classic radiators .