SATA II hard drive bios detection problems?

ooh ooh ooh i might know this one. this thing drove me nuts for a few days. see if it reliably can detect it when rebooting, and pretty much never detects it in a cold boot. if that is true, my problem was the drive was not spinning up fast enough. so there was an option in the BIOS called HDD DELAY. meaning when detecting the hard drive, it pauses for the amount you set in the delay, giving the drive time to power up. it fixed my problem completely. good luck