(full disclosure: I run the Belgian/Dutch QNAP community forums which are independent user forums; I'm also a beta tester; I am, however, not employed by QNAP at all and you can find plenty of negative talks by me on their forums as I try to stay balanced)
Since the news is somewhat out due to the Computex announcement, I thought it might be interesting to mention a new QNAP NAS model. No, I'm not talking about the HS- and IS- fanless models, I'm talking about the TS-x51 range.
Ever since the dreaded TS-209 with its noisy fan (for me), QNAP has been getting a bit better in the noise department, but with the TS-x69 range this stopped (it was actually worse). Now, however, I think we have a new winner.
I've had a TS-451 on beta test for a while now, and I can easily say it is the most quiet NAS I have had here (I haven't had any fanless models). This article has more tech specs: http://www.businesswire.com/news/home/20140604005315/en/QNAP-Showcases-Generation-NAS%C2%A0--TS-x51-Home-%C2%A0SOHO#.U6H3QaYjtFY
Basically, it runs a low power dual-core Celeron 2.4GHz with low voltage DDR3 ram, and (except for the 2 bay model) has a nice big slow-turning fan at the back. I'm impressed with it. My other NASses are hidden away, this one is currently on test in my living room.
The price will probably be premium, this is QNAP after all, but it is targeted at home, and it's by far the fastest home/homeoffice NAS I have seen (currently stuffed 8GB ram in it and running debian in a VM).edit:
found a better link with more info: http://files.qnap.com/news/pressresource/datasheet/TS-x51Series-%28EN%29_51000-023608-RS.pdf