EVGA is a video card maker, they don't make motherboards. EVGA's motherboards are made by FOXCONN which is a major maker of low end boards, they make them for EVGA,BFG,ECS and a few others.
They are generally stable no frills boards but don't normally have a good reputation for overclocking, and are not known for great bios support. They first broke into the enthusiast market with an nforce4 SLI board that was a decent but not top tier overclocker. It remains to be seen how well their 680i board will do, they are using the standard nvidia reference board design which many reviewers have had great overclocking sucess with. My guess is they will be good overclockers because of the 680i chipset, but will probably not compete well against the top tier 680i boards that will utilize better quality components and have superior bios development geared toward enthusiasts like the upcoming Asus and DFI boards