Computer Won't Start Without Clearing CMOS

Capt Proton

Distinguished
Oct 17, 2007
5
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18,520
Long time since I've been here. Rig specs are out of date, will update as soon as I can figure out how to. Shouldn't make any difference to my problem.
Noted over past few months that it was becoming more and more random how many times I had to press the power switch to start the rig. Thought it was the power switch itself failing.
Two days ago, rig would not power on at all. Checked power and power supply, all seemed well. Finally cleared the CMOS. Rig powered up, I went into the BIOS and loaded my standard settings, rig booted and behaved normally. Shut down at end of day. Next morning, same sequence of events. No power at all, clear CMOS, rig powers up, and boots cleanly after resetting CMOS.
I also loaded auto settings and just changed what I had to so rig would boot. No difference to behavior.
Thoughts? CMOS battery?