Chaintech VNF4 Ultra Zenith VE. Hands-down, no contest. It's ultra-stable, highly overclockable and cheap. The only issue I've ever seen or heard is the way the memory slots are placed makes it impossible to use RAM with the obnoxious LED displays on the top, i.e. Corsair XMS extreme, etc.
I've got a Chinatech (sic) 6600GT as well. Both have been excellent out-of-the-box performers and both have been superb overclockers. Small company, attentive to customers, good stuff all around.
Not the quality of a DFI board for example, but you get what you pay for.
