I've got a DQ67SW (I think), BIOS is SWQ6710H.86A.0061.2012.0210.1130
My hard drive (which is using GRUB 2) is the only bootable device (and first on the boot list). When I try to boot, it says: A bootable device has not been detected. Please refer to the Product Guide at http://support.intel.com/support/motherboards/desktop/ http://support.intel.com/support/motherboards/desktop/. (the product guide didn't help much) But if I press F10 on bootup (to get the boot menu), select the hard drive and press return, it boots.
So it's clearly getting itself into a bit of a kerfuddle.
Edit: the question is, how do I get it to boot straight to the hard drive without prompting? given the above.
Try adding a hard disc pre-delay in the BIOS under drive configuration. Not sure what the minimum value is for your board, maybe 5 seconds? Try that and see if things boot properly.
Some other things to consider and try, which SATA connector on the motherboard is the HD connected to? SATA port 0 would be ideal. Also, if you do an install of an OS and then move the drive to a different SATA port, you could experience boot problems. I'm almost thinking this is a problem with how you installed the OS and the grub 2 bootloader.
If you have a spare drive or don't care what's on the drive that doesn't boot properly, do a fresh install of Ubuntu from CD or USB stick, telling the installer to use the entire drive and overwrite any existing OS's and partitions. When the install is complete you should have no trouble booting from the hard drive.