It might be your 400W PSU. You might be pushing it too hard. Just a thought. A better PSU can't hurt anyway.
In fact, I'm beginning to suspect the mobo. It has an on-board video adapter, which takes memory from the main memory banks. Maybe this causes some conflict with the PCI x16 slot or the Perc.
Edited by microkid - 3/31/09 at 10:45pm