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What happens if I clear CMOS when running the computer?

Originally posted by: steimm
Might seem to be a stupid question, but what happens if I accidently would clear CMOS when the computer is up and running?
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Just how do you accidentally clear the CMOS when the computer is up & running? 😕

No, I don't know the answer to your question, sorry.
 
I haven't done that - I'm just wondering what would happen if I did that.

I'm just thinking there is room for another product on the market...
 
Originally posted by: steimm
Might seem to be a stupid question, but what happens if I accidently would clear CMOS when the computer is up and running?
Click to expand...

I don't think anyone has ever accidentally done it. I'd imagine that there could be various results on a hardware or software level.

My tip to you: Don't do it.
 
Not a good idea since you should unplug all your power connectors from your motherboard before clearing CMOS . . . there's a reason for that . . . 😉
 
I'm not sure it's even possible.. Usually you put a jumper in the right place and when you next turn it on, it clears it then. I don't think removing the battery would clear it either, while it's switched on.. You'd have to switch it off for a while.

But hey, if you wanna try it.. 😛 I think if you did somehow manage it, it _might_ not affect anything until you tried to reboot it..
 
Well there is surely a risk to CLRCMOS without removing all the cables, but that is something that I never do. I have always cleared CMOS with power cable connected to PSU but of course with the computer turned off.

And I sure do understand that it is no good idea to clear CMOS while it is running, but I was just curious if someone knows what would happen. I haven't tried it yet, but what can really happen?

- Crash boom bang - everything goes black? All the stuff inside the computer destroyed for all future use?
- Crash boom bang - everything goes black, but it would work after a cold boot again but w/ risk for BIOS is crashed?
- Nothing at all until you reboot and BIOS is destroyed?
- Nothing at all until you reboot and BIOS-settings is back to original?
- Nothing at all?
 
by the way, I have done several "hot flash" of BIOS and that is no problem - but that might not have anything to do with CMOS - or?
 
Originally posted by: toot
I'm not sure it's even possible.. Usually you put a jumper in the right place and when you next turn it on, it clears it then. I don't think removing the battery would clear it either, while it's switched on.. You'd have to switch it off for a while.

But hey, if you wanna try it.. 😛 I think if you did somehow manage it, it _might_ not affect anything until you tried to reboot it..
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no you do not turn it on with the cmos jumper in the clear position. you turn off your machine, disconnect all power from the machine and 30seconds. then you move the jumper over to the clear position and wait 30seconds. then put it back to the normal position, reconnect power and go.
 
Originally posted by: eplebnista
Originally posted by: evilharp
Originally posted by: steimm
Might seem to be a stupid question, but what happens if I accidently would clear CMOS when the computer is up and running?
Click to expand...

My tip to you: Don't do it.
Click to expand...

I concur!
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But hey -- if you do, make a video of it and share with us!

... I've always wondered what would happen if you slammed your transmission into Rev while going 55... Anyone want to try and find out?
 
Originally posted by: severtki
Originally posted by: eplebnista
Originally posted by: evilharp
Originally posted by: steimm
Might seem to be a stupid question, but what happens if I accidently would clear CMOS when the computer is up and running?
Click to expand...

My tip to you: Don't do it.
Click to expand...

I concur!
Click to expand...

But hey -- if you do, make a video of it and share with us!

... I've always wondered what would happen if you slammed your transmission into Rev while going 55... Anyone want to try and find out?
Click to expand...

lol - I understand the point - as I have stated, but I thought that someone in here actually knew... But don't compare mechanics with electronics - I don't think that's really fair.

I have a reason to ask this, but before I do anything I'd like to know if there really is current on the three pins for CLR_CMOS. Ok, I know it might differ between the brands and models.

I don't really understand why it would happen anything at all. BIOS and CMOS is not used (or?) when I'm in Windows-mode.

 
Originally posted by: steimm
Might seem to be a stupid question, but what happens if I accidently would clear CMOS when the computer is up and running?
Click to expand...

Probably nothing.

I have hotflashed BIOS before and in doing so you actually remove the BIOS chip and replace it with another (while the computer is in use). Doesn't seem to hurt anything.

I think when it's running, the important parts of the BIOS are moved to RAM.
 
Same results as slamming that auto trannie into reverse at 55mph. NOTHING GOOD will happen to be sure. Only difference ... your mobo is cheaper than a transmission.
 
I beleive you might corrupt your BIOS if it isn't protected enough from these "intentional accidents "go ahead and do it but don't come back to the forums crying about your BIOS / MOBO.
But if you still have the urge to do it, get some old cheapo sub $ 50 PC from Ebay and do all kinds of crazy expirements like I used to do.
No matter what happens leave your main rig alone, got the hint 😉
 
I sure got the hint ;-)

But back to business, what it is REALLY going to happen? There is a lot ppl that "knows" but is it anyone that really KNOWS?
 
Originally posted by: NotquiteanooB
Same results as slamming that auto trannie into reverse at 55mph. NOTHING GOOD will happen to be sure. Only difference ... your mobo is cheaper than a transmission.
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Are you 100% sure of that?
 
Originally posted by: steimm
I sure got the hint ;-)

But back to business, what it is REALLY going to happen? There is a lot ppl that "knows" but is it anyone that really KNOWS?
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nobody around here stooopid enough to do this. go to another forum and ask there
 
Originally posted by: steimm
I sure got the hint ;-)

But back to business, what it is REALLY going to happen? There is a lot ppl that "knows" but is it anyone that really KNOWS?
Click to expand...

How can this be ?back to business?? This whole thread is asinine. Why not just fess up? Reboot the damn box and let us know what happens! Geeezzzz, what a waste of time and bandwidth.
 
The CMOS RAM is only fed by the battery when there is no other source of power. Even in ATX "off" mode, it's fed by the power supply through the +5Vstandby rail.

The "Clear CMOS" jumper has the battery current run through it. When you pull it or set it to the "clear" position, what you're actually doing is disconnect the battery.

So, if you move the "CMOS Clear" jumper while the system is on a (standby or fully) powered ATX PSU, absolutely nothing would happen to CMOS RAM contents. All that remains is the risk of an ESD zap 😉

(Disclaimer: The above is true for typical mainboard implementations. Some might have the jumper in the resulting power feed to CMOS, and some others might always run the CMOS RAM on battery. YMMV.)
 
Originally posted by: doc2345
Originally posted by: steimm
I sure got the hint ;-)

But back to business, what it is REALLY going to happen? There is a lot ppl that "knows" but is it anyone that really KNOWS?
Click to expand...

How can this be ?back to business?? This whole thread is asinine. Why not just fess up? Reboot the damn box and let us know what happens! Geeezzzz, what a waste of time and bandwidth.
Click to expand...

:laugh:
 
Originally posted by: Peter
The CMOS RAM is only fed by the battery when there is no other source of power. Even in ATX "off" mode, it's fed by the power supply through the +5Vstandby rail.

The "Clear CMOS" jumper has the battery current run through it. When you pull it or set it to the "clear" position, what you're actually doing is disconnect the battery.

So, if you move the "CMOS Clear" jumper while the system is on a (standby or fully) powered ATX PSU, absolutely nothing would happen to CMOS RAM contents. All that remains is the risk of an ESD zap 😉

(Disclaimer: The above is true for typical mainboard implementations. Some might have the jumper in the resulting power feed to CMOS, and some others might always run the CMOS RAM on battery. YMMV.)
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Thx for a great reply!

 
Originally posted by: steimm
by the way, I have done several "hot flash" of BIOS and that is no problem - but that might not have anything to do with CMOS - or?
Click to expand...

That kind of stuff happens when the CMOS hits menopause...

J/K

I've done that before. Way back in the day there used to be information on how to do that on Shuttle's web site.

Peter's explanation was pretty clear, but what I don't get is why someone didn't just try it. I was about ready to walk down to the garage and pick out a spare board to try it reading down the thread until I got to Peter's post.
 
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