You wont regret getting a saphire, I just picked one up and its great for both over and underclocking.
Underclocking goes all the way down to 545/[email protected], 666/[email protected]
Does 925/150 on stock vcore no probs - gets a bit hot tho in my Shuttle mini box and I dont like stressing the 300w PSU.
In my rig which idles at 50w no load, this card only adds 40-45w @ 666/[email protected] (so it goes from 50w to 95w loaded, measured at the plug)
Does about 105w-110w at stock speed and voltage, so underclocking is well worth it for me (im on offgrid solar so I need to sip the power)
So im pretty happy with this card.