If you really want to go this path.....my first suggestion would be to update every driver you can find especially usb and m/b bios.....(yes, a catch 22 with no OS installed)
Second, ... there well could be a small fault with the board but being a P35, RMA would probably be out of the equation .... instead of beating yourself up, I would just burn your USB to disc and boot from disc ...at the very least this should narrow the error down to just a couple of areas or prove there is a larger underlying problem....Try the disc first.
Aussie Allan