Thanks for the compliment.
I am using an older system:
X2 4200 939 (TDP 89W) @2600Mhz
3870 graphics card small overclock
250gb WD laptop disk 5400rpm
Creative eXtreme Music sound card
TV tuner card
2 Nexus fans
Vista Ultimate 32bit SP1
To answer your question it is not a power hungry machine. The fan in the PSU was way too loud even at idle. When i first installed it i had 2 extra 3,5" disks in and the PSU was the loudest part in my PC.
It is possible that mine was defected because i cant imagine that people on this site would call this thing quite. My friend ordered the 550W unit and it has the same problem. I don't know if we got some bad units but as we had ordered them from another country it just didn't make any sense to send them back.
If you should void your warranty that is something you have to decide for yourself. For me it was fairly simple as i was not going to send it back anyway. What i can tell you is that at idle it is more or less silent, my two Nexus fans make more noise. And at load i don't hear it because when i play games i increase the voltage of the fan that is blowing on my graphics card from 6 to 9V.
I for one am very happy that i did this. The PSU is now close to silent and the air that is being vented (not much air) is cool.