I know this will seem like an odd question but is it really silent? and was it worth the price?
Well it was just under 100€ and corsair's HX520W was the same price here, so yes it's worth the price
I was going for ZM500-HP as first, but it was just 10€ cheaper than this 600w version, so not really a hard decision.
Has been silent so far, the fan speed turns up depending on load not temperature and like I said my system is not pushing it to the limits. Found this little diagram to give you and idea
"In the ZM600-HP the fan started out from 1000rpm and stopped at 1600rpm."
http://www.xbitlabs.com/images/other/atx-psu7/11gr5.png
Just opened side panel and touched the side of the PSU and it's almost cold to touch
Back end is "warm" as the heatpipethingy is there, but barely any air comes out, so I'm quessing it's going that 1000rpm now.
I'll go take couple 40mm 5V fans out (they were sucking out GPU hot air trough the card slots for summer) and turn VF900 to 5V. Then I'll spin the atitool cube and burn cores with Intel TAT and listen if I hear the PSU
EDIT: so did some load testing and couldn't hear a thing from the PSU. TAT with 100% on another core and atitool cube spinning for 10min. Both cores with TAT and there wasn't enough CPU power left to spin the cube more than 25FPS
Bare in mind I have 3x80mm 17db 1600rpm and 2x92mm 19db 1600rpm (one is cpu cooler) running in the system, but all fan noise is low hum and not irritating. If you have only 1 system fan and a silent cpu cooler you might hear something. Though that systems airflow is so low (my case fans are combined 52CFM in and 60CFM out) that I doubt it will be used for high end gaming rig and PSU won't be pushed anywhere near the limit and it will still be silent
Hope this answered your question