I have got two of these on my HD5870s and temp. goes down from 5-12C while playing GTA IV or CoD6 on max.
If you going to buy it it has already a fan control mounted in.
i would recommend using msi afterburner. i just installed it a couple of days ago and i will never use ccc again (unless configuring eyefinity). it is a lot easier to use for ocing and you can set hotkeys for different settings (i.e. a specific oc with a specific fan speed). it also has a fan speed setting.
i just installed ccc 10.1 and i have the hd 5770 and i have manual fan control. i am looking at it now. why would the hd 5770s not get it? that wouldn't make any sense.
Just installed my 5770. You do have fan control. Go into CCC, scroll down to ati overdrive. Click the lock to unlock control and your manual fan speed.
nevermind guys. i ended up reformatting and it solved all my problems. CCC now gives me fan control, tessellation works in unigine and dirt2 gives me Dx11 (although dirt2 is still cuaisng me other issues.)