Overclocking with advanced air-cooling can take Intels Skulltrail platform from 3.2 GHz to 4 GHz pretty easily, even our review showed that. Now, 4.5 GHz is manageable with a modest water-cooling system. Not surprisingly, there is a lot more capability in this platform if take an extreme Skulltrail a bit more extreme.
According to a forum post on XtremeSystems, an overclocking community sites,
Overclockers push 8-core Skulltrail to 6 GHz
