I turn on my computer, it beeps once and then it goes to "checking NVRAM" i wait for about a minute and the it says "Reboot or select proper boot device". I have tried almost everything, from changing my cables to my HDD removing the battery, trying a new battery, removing all cables except the necessary ones. Its a new mobo...I bought it because my old computer would never boot/turn on and if it did it would crash and not turn back on.
If so, check to see the boot order and what boot devices are enabled.
I'm going to assume your OS is on an internal HDD...does it show in the BIOS as a bootable option? Is it sequenced as the first bootable device? What type of HDD is it, IDE, SATA? If IDE, have you checked the master and slave jumpers?
Lastly, do you know if the OS had any issues...any system files that became corrupt?