On my board when using the original over-clock settings I used with 10.8.0 which allowed sleep, after the 10.8.2 update it will no longer sleep. The display will sleep but the fans will continue to spin on the machine and the display will not wake up again - necessitating a reboot. I have done no investigation of it yet other than to very quickly create another over-clock configuration with everything on auto - this gives me sleep functionality back again. To be honest I don't really use the over-clock and do not have the time at the moment to dedicate to investigating it.