Gaming benchmarks
The following tests are run with a discrete Radeon HD 6950 2GB card installed.
The Gigabyte Z68 wins a test but also pitches in at the bottom of a separate gaming benchmark. However, there's very little to differentiate the Intel boards.
IGP
One can switch between discrete and onboard graphics by dint of the Virtu emulation software bundled on the driver CD. Forcing the IGP (with a 256MB framebuffer) results in a 3DMark Vantage score of 1,728, a Call of Duty score of 31.3fps (720p setting) and StarCraft II benchmark of 20fps (720p setting).
Ideally, assuming a discrete GPU is the primary video adapter, you'll want to force the IGP active in situations - relating to power consumption - where it makes implicit sense to do so: QuickSync video and 2D tasks.
CPU overclocking
Adding just a touch of voltage to the CPU core and chipset, we topped out at 4.7GHz (47 x 100MHz clock) from our trusty Core i5 2500K chip. The overclock is consistent with that achieved on other Z68 boards.