Boot order changes by itself


R

Rebel1

After being away from my desktop for a month, last night I plugged the
power cord back into the wall outlet and booted without any problems. I
performed various tasks for several hours and shut down normally. This
morning when I tried booting I got a message something like NTLDR is
missing. Since I had this same problem two months ago, I knew what to
do: in the BIOS change the boot sequence from one of the two physical
hard drives to the other.

But what's causing the BIOS to change the boot order? The previous
session, there were three program updates: Firefox, Thunderbird, and
Adobe reader. I'm not blaming any of those updates, but mention them for
completeness.

W8.1. AMD Asus M3A76-CM mobo.

Thanks for your suggestions/comments.

R1
 
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P

Paul

Rebel1 said:
After being away from my desktop for a month, last night I plugged the
power cord back into the wall outlet and booted without any problems. I
performed various tasks for several hours and shut down normally. This
morning when I tried booting I got a message something like NTLDR is
missing. Since I had this same problem two months ago, I knew what to
do: in the BIOS change the boot sequence from one of the two physical
hard drives to the other.

But what's causing the BIOS to change the boot order? The previous
session, there were three program updates: Firefox, Thunderbird, and
Adobe reader. I'm not blaming any of those updates, but mention them for
completeness.

W8.1. AMD Asus M3A76-CM mobo.

Thanks for your suggestions/comments.

R1

Agree on the CMOS battery.

But on Asus, there is a second possibility. If the computer
crashes in POST, the BIOS can auto-reset the settings to
stable values. It's a way to fix an overclock so the user
is put back in control. I've had problems with this
happening "spontaneously" before, and it's the recovery
mechanism doing it. Cranking down the overclock, helped :)
(On Asrock, it takes three pushes on the RESET button
to do the same thing, reset the BIOS settings.)

But if you know it's a CMOS battery problem, then that's
the cure. The CMOS battery discharges in 2.8 years, if you
switch off or unplug the PSU. If you leave the PSU in the
ON position, so +5VSB flows to the motherboard, the CMOS
battery can last as long as 10 years (i.e. shelf life value).
It's then a matter of budgeting mains power pricing, to
leave the wasteful PSU running, versus the replacement
cost of a battery if you decide to disconnect the mains
each night.

Paul
 
M

Michael Black

Agree on the CMOS battery.

But on Asus, there is a second possibility. If the computer
crashes in POST, the BIOS can auto-reset the settings to
stable values. It's a way to fix an overclock so the user
is put back in control. I've had problems with this
happening "spontaneously" before, and it's the recovery
mechanism doing it. Cranking down the overclock, helped :)
(On Asrock, it takes three pushes on the RESET button
to do the same thing, reset the BIOS settings.)

But if you know it's a CMOS battery problem, then that's
the cure. The CMOS battery discharges in 2.8 years, if you
switch off or unplug the PSU. If you leave the PSU in the
ON position, so +5VSB flows to the motherboard, the CMOS
battery can last as long as 10 years (i.e. shelf life value).
It's then a matter of budgeting mains power pricing, to
leave the wasteful PSU running, versus the replacement
cost of a battery if you decide to disconnect the mains
each night.
Well people keep their computers on for more reasons than making the
battery last longer. I doubt anyone really leaves it on for that reason.

If nothing else, it seems like any time I turn off my computer, I
immediately remember something more I needed to do on it. So yes, I tend
to keep it on.

But if someone is cheap about the battery, the simple solution is to get a
larger capacity battery, and wire that in. I had a nice LCD clock, a
display larger than many, that I got years ago, and when the button cell
finally died, I couldn't be bothered to look for a replacement and spend
the money, so I soldered an AA battery into the clock, and left it hanging
outside the case. That just lasted forever. Of course it helped that it
originally ran off 1.5V.

Michael
 
R

Rebel1

Thanks, everyone, for the battery suggestion. So simple. I'll followup
on it.

R1
 
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Y

Yousuf Khan

After being away from my desktop for a month, last night I plugged the
power cord back into the wall outlet and booted without any problems. I
performed various tasks for several hours and shut down normally. This
morning when I tried booting I got a message something like NTLDR is
missing. Since I had this same problem two months ago, I knew what to
do: in the BIOS change the boot sequence from one of the two physical
hard drives to the other.

But what's causing the BIOS to change the boot order? The previous
session, there were three program updates: Firefox, Thunderbird, and
Adobe reader. I'm not blaming any of those updates, but mention them for
completeness.

W8.1. AMD Asus M3A76-CM mobo.

Thanks for your suggestions/comments.

I used to have the same problem. It seems to get caused by plugging
external USB or eSATA hard drives into the machine, even if you're not
going to boot from those devices.

Yousuf Khan
 
F

Flasherly

I used to have the same problem. It seems to get caused by plugging
external USB or eSATA hard drives into the machine, even if you're not
going to boot from those devices.

Ditto, along with a whole bunch of mess with installing a SSD
(similarly related). Same goes for moving around HDDs on s/pata
cables. Second time up, migrating the old SSD for a new, happened to
catch on. New game plan, evidently, is to watch for BIOS drive-boot
assignment switcheroos, whenever messing with it (what it was, no
longer if a change takes place). Cool new game: Semi- or almost-SMART
(for something maybe) BIOS features. Can hardly wait to migrate to an
all-GOOEY BIOS.
 
L

Loren Pechtel

After being away from my desktop for a month, last night I plugged the
power cord back into the wall outlet and booted without any problems. I
performed various tasks for several hours and shut down normally. This
morning when I tried booting I got a message something like NTLDR is
missing. Since I had this same problem two months ago, I knew what to
do: in the BIOS change the boot sequence from one of the two physical
hard drives to the other.

But what's causing the BIOS to change the boot order? The previous
session, there were three program updates: Firefox, Thunderbird, and
Adobe reader. I'm not blaming any of those updates, but mention them for
completeness.

Failing CMOS battery, perhaps?
 
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R

Rebel1

Failing CMOS battery, perhaps?

I did change the CMOS battery and haven't had the problem since. But I
won't go out on a limb and say this was definitely the cause of problem.
Other have raised valid possibilities.

R1
 

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