Did you check that motherboard battery Warbler?

Symptoms of a Dead CMOS Battery

"A dead or dying CMOS battery may cause your computer to take a long time to boot up. This is because your computer has to actually recreate the BIOS settings from scratch every time you reboot. Figuring out the number and location of hard drives, the available amount of memory and other information necessary for booting may cause your computer to delay significantly. This can also cause the computer to run at the wrong speed, since the BIOS settings aren't retained. A computer with a bad CMOS battery may refuse to boot entirely."