I have a Shuttle ST20G5. The PSU died so I hooked up a regular size ATX power supply to it to get it running. In the process of figuring out the PSU was dead I did the CMOS reset.

Now when I boot the computer can not find a boot device.

I have two drives one PATA and one SATA both show up in the BIOS. Windows is on the SATA drive. The BIOS is set to boot from HDD for all the boot devices you don't get to specify which one.

I booted into Ubuntu from a thumb drive and both drives show up in there and I can see files on both drives.

I am guessing this is something simple I am missing.