How long does it take a CMOS battery to discharge?

[Ichigo]

Messed with some BIOS settings in an old comp, now it beeps non-stop during boot. Can't get anywhere. No manual, so I don't even know what jumpers to mess with.

So now I'm letting my CMOS battery just lay here for a while. =/

 

[Fern]

Unplugg the PC too.

Once when getting too aggressive with an OC I had to leave the battery out overnight to get the CMOS to clear.

Usually just takes a few minutes.

Fern

 

[Ichigo]

What I did specifically was change DDR to 400 from 333, which is the most likely culprit.

But this is definetly a BIOS/CMOS issue, right?

 

[Machine350]

Yeah, if you've got budget PC2700 Ram, it most likely will not work at ddr400. Do a search on overclocking and you will find more info here than you know what to do with. But to answer your question, you generally just unplug the system, switch the CMOS reset jumper, leave the battery out for at least 15 seconds, switch jumper back, reinstall battery, plug back in. Just make sure to reset what you changed in the bios.

 

[Ichigo]

It's been 2 hours, I just tried again, and still the same beeping issue, not booting up.

Guess I'm stuck leaving it alone for a while.

And by the way, I left the jumpers (the ones right beside the CMOS battery slot) in the reset poition (I think). It's fine to leave it there for the hours I'm waiting, right?

 

[Ichigo]

I also tried putting in a stick of PC3200 512MB RAM. Did the same thing. Now I'm scared.

 

[fire400]

i recall cmos's resetting after a few minutes when you pull them out

 

[Missing Ghost]

I'm not too sure of how the cmos ram works, but I have a little idea. cmos ram is like little capacitors that keep value. If you leave the cmos battery or the standby current in, the ram gets refreshed all the time and does not lose the values. If you both remove the battery, standby power AND put the jumper on reset position, the litte cmos ram's capacitors get discharged in a resistor. Then you can put the jumper back in not-connected position (normal position), replace the battery and standby power, and all the settings are gone. If you don't use the reset cmos jumper the ram should lose the values within 30 min. Or something. BTW, to remove standby power, put the switch on the back of the ATX psu to off, or unplug the ac cord.

 

[Ichigo]

I've done this, from what I can understand.

But it's still not working. My last hope is to wait overnight or something. All was fine before I decided to tamper with the BIOS.

 

[Fern]

No manual, so I don't even know what jumpers to mess with.

Most manuals can be downloaded. Fire up google and get one. Check for beep codes with google too.

Did you change anything in BIOS other than the ram frequency?

Double check wiring/connections to make sure you didn't accidentily loosen anything while you were working in the case.

If all you've done is change the ram's frequency not likely that anything is damaged. Don't worry.

Fern

 

[JimPhelpsMI]

Hi, Two hours is usually enough, but it really depends on the guy that designed the MB and the size of the caps he used in the CMOS circuit. That's what you are waiting for to discharge. Best is to locate the jumper. Try the board maker if you can find it. It disconnects the battery and shorts out the caps. Discharge is almost instantaneous. AC POWER MUST be disconnected from the wall outlet if the PSU doesn't have a switch on the back with either method. You can also short across the empty battery holder on some MBs to get a fast discharge, but only if you know what you are doing. Hope this helps a bit, Jim