I have owned this board for a few months now and I have mixed feelings about it to be honest. It certainly well known that the X48 platform is not the easiest platform for over-clocking quad core CPU's. Wish I had read that before I bought it!
I have a Q9650 running on my board, it has a reasonably high VID of 1.275v so runs cooler than most at higher VCore settings but conversely it requires more core voltage to get to higher over-clocks.
I can get my Q9650 to 4GHz stable on this board, with 1.393v at the core. I wouldn't go much higher to be honest as I would be risking CPU degradation. If you want to over-clock quads then I recommend a good P45 chipset board such as the EP45-UD3R or UD3P. These are kings at over-clocking quads.
However the X48 chipset benefits from 2 x16 PCI-E slots. Which is a bonus when running two graphics cards.
The Bios features are ok, but better on the P45. The latest BIOS is the F3B version, still listed as a beta on Gigabytes website, as it has for many, many months.
Overall it is hard to recommend the board over it's P45 counterparts. The 2 x16 lanes are a boon for sure, but one x16 and a x8 slot on a P45 is not going to reduce your FPS by a great deal and the extra over-clocking headroom on the P45 would no doubt make up for this issue.
It's a stable board for sure but didn't light my fires!