A weird power issue on a Dell OptiPlex 3080 took me 4 hours to fix

Had a client bring in a Dell OptiPlex 3080 that would not turn on at all. No lights, no fan spin, nothing. I swapped the power supply with a known good unit, same problem. Checked the front panel button, that was fine. I was about to call it a dead board when I decided to pull the CMOS battery. It read 2.8 volts, which seemed okay, but I put a fresh one in anyway. The thing booted right up. I put the old battery back in to test, and it failed again. A weak CMOS battery, not fully dead, was stopping the whole system from starting. I've seen them cause boot loops or time errors, but never a complete no-power situation. Has anyone else run into a CMOS battery causing a total power failure like this on newer machines?

3 comments

3 Comments

king.lisa25d ago

That's wild. A CMOS battery causing a total brick? Seems like a weird fluke. Maybe there was something else going on too.

victor_barnes4825d ago

Yeah the "weird fluke" part is so true lol. I had an old desktop that would not post at all, just black screen and fans going crazy. Swapped the CMOS battery on a whim and it booted right up like nothing happened. Felt like some kind of voodoo magic, man. Those little batteries can cause the strangest problems for no good reason.

king.lisa4d ago

Honestly it makes sense when you think about it... that battery keeps the basic settings alive. Without it, the board might get totally confused about what to do first. I've seen them cause wrong clock speeds and boot loops, but a full no-post is next level. It's like the computer forgets how to be a computer for a second.