ASUS's GPU Tweak software initially debuted with the HD 7970 at the start of this year and since then it has gone from a buggy mess to a usable and polished tool for overclocking GPUs. Curiously, the latest 188.8.131.52 version still interfaces with the Nvidia driver API, providing only regular GPU Boost parameters and locking out actual access to the GPU voltages above 1.175v. The power cap on this board can be raised to a meagre 117% which sadly is not going to be breaking any world records.
With the fans set at 100% and using the very unforgiving Furmark 1.101 stress test, we registered an acceptable temperature of 59 degrees celcius at stock and 64 degrees celcius when overclocked, which is below the 70 degrees throttling threshold enforced by GPU Boost. Normal games and applications should run way cooler this this.
By default, the ASUS GTX 670 DirectCU II TOP comes factory overclocked an impressive 157MHz higher than the default core boost clock of 980MHz. Unfortunately, we were only able to maintain stability with +20MHz more after that and also a marginal +75MHz on the memory clocks. Note that the card we had was from a local retailer's stock and not a cherry-picked media sample.