i have a k8v se deluxe with a WD 120GB HD and it works fine
Have you installed windows/drivers for it?
Also if you have just the K8V model and not SE or deluxe...maybe a bios flash with a newer version could help?
I also have the 4pin molex hooked up to it...you don't need the SATA power
Q6600 G0 @ 3.80ghz
MCR-320-->Dtek Fuzion V2-->Dtek Fuzion GFX2-->Swiftech MCP-655-->
Asus P5K deluxe
4x1gb Crucial Ballistix @ 846mhz 5-5-5-15
3x 250gb HDDs
Coolermaster 690 w/ water cooling mods
3dmark06 - 15,602
SuperPi 1M - 12.421s