random reboots

[Mathew Duafala]

I have a homebuilt system with the following.
Asus A7N8X mobo (rev 2.0)
athlon XP barton 2800
2 512 PC3200 samsung Ram chips
ATI Radeon 9600 All in Wonder

After running the computer fine for about 4 months, I am now getting
random reboots and shutdowns. When the machine shutsdown without
rebooting, it leaves the power LED on and it won't restart until I
unplug it and let it sit for about 10 seconds. Then I can plug it
back in and reboot.

I am pulling my hair out trying to track it down. The things I have
tried

-resetting the bios (which drops the FSB to 133 from 166)
-lowering the RAM speed
-disabling the onboard LAN and SCSI devices
-Checked the power supply (both with a multi meter and with asus
probe)

After having the system for about a month I overclocked it to 3Ghz for
a couple of days (Didn't really notice a difference so I reset it).
It was stable while overclocked (ie I burned it in).

Any ideas what it could be? As an aside, the power switch on the case
just went bad (Antec Sonata) so I switched the power to the reset
button. Seems to work fine now. Could this be a short somewhere?
The temps stay down the safe range.

Thanks,
Mat

 

[Paul]

I have a homebuilt system with the following.
Asus A7N8X mobo (rev 2.0)
athlon XP barton 2800
2 512 PC3200 samsung Ram chips
ATI Radeon 9600 All in Wonder

After running the computer fine for about 4 months, I am now getting
random reboots and shutdowns. When the machine shutsdown without
rebooting, it leaves the power LED on and it won't restart until I
unplug it and let it sit for about 10 seconds. Then I can plug it
back in and reboot.

I am pulling my hair out trying to track it down. The things I have
tried

-resetting the bios (which drops the FSB to 133 from 166)
-lowering the RAM speed
-disabling the onboard LAN and SCSI devices
-Checked the power supply (both with a multi meter and with asus
probe)

After having the system for about a month I overclocked it to 3Ghz for
a couple of days (Didn't really notice a difference so I reset it).
It was stable while overclocked (ie I burned it in).

Any ideas what it could be? As an aside, the power switch on the case
just went bad (Antec Sonata) so I switched the power to the reset
button. Seems to work fine now. Could this be a short somewhere?
The temps stay down the safe range.

Thanks,
Mat

1) Check temperatures, fan speeds, and voltages in the hardware
monitor.
2) It could be the power supply. Does the PSU get hot to the touch,
as in too hot to keep a finger on it ? Are the voltages off
by more than 5% ?
3) Test things in sequence. Memtest86 for memory. Prime95 for CPU.
3DMark to cover the AGP slot and the video card (use demo mode
and use a copy of MBM5 to record temps and voltages while
the test runs). Using those tests, you may get some more symptoms
to work with.

Generally, when a system shuts down, some hardware is trying to tell
you it is in trouble. If you insist on running the system in its
current state of discomfort, it will eventually fail, and sometimes
the damage caused can be expensive. Finish your testing as quickly
as possible, to reduce the risk of creating an expensive problem.

I learned a lesson similar to this with a hard drive. I could hear
sounds like something was wrong with the head or actuator, but
said to myself "I'm too tired to do a backup tonight - I'll do
it tomorrow". Of course, when tomorrow came, the disk was dead.

There was a poster here, who had the "AGP warn" LED light on the
motherboard, indicating he was using an incompatible video card.
He said "I must have pressed the power button 50 times, until it
started". Of course, the incompatible AGP voltage fried the system.
If what is happening to you is a protection mechanism cutting in,
the form of protection might not be bullet proof enough to use
forever.

I take it, as this is an Nforce2 board, that the CPU and RAM are
running at the same speed ("100%") ? The Nforce2 works best if
the CPU and RAM work in sync - otherwise you may find memory errors
crop up in memtest86.

HTH,
Paul

 

[Triffid]

I have a homebuilt system with the following.
Asus A7N8X mobo (rev 2.0)
athlon XP barton 2800
2 512 PC3200 samsung Ram chips
ATI Radeon 9600 All in Wonder

After running the computer fine for about 4 months, I am now getting
random reboots and shutdowns. When the machine shutsdown without
rebooting, it leaves the power LED on and it won't restart until I
unplug it and let it sit for about 10 seconds. Then I can plug it
back in and reboot.

I am pulling my hair out trying to track it down. The things I have
tried

-resetting the bios (which drops the FSB to 133 from 166)
-lowering the RAM speed
-disabling the onboard LAN and SCSI devices
-Checked the power supply (both with a multi meter and with asus
probe)

After having the system for about a month I overclocked it to 3Ghz for
a couple of days (Didn't really notice a difference so I reset it).
It was stable while overclocked (ie I burned it in).

Any ideas what it could be? As an aside, the power switch on the case
just went bad (Antec Sonata) so I switched the power to the reset
button. Seems to work fine now. Could this be a short somewhere?
The temps stay down the safe range.

Thanks,
Mat

A bad power switch would certainly explain the symptoms - so you have
likely answered your question (and worked around the problem).

 

[Mathew Duafala]

1) Check temperatures, fan speeds, and voltages in the hardware

monitor.

All the fans turn on and seem to run at reasonable rates. I don't
know what the rpm is supposed to be for them, but they are all moving
a fair bit of air.

2) It could be the power supply. Does the PSU get hot to the touch,
as in too hot to keep a finger on it ? Are the voltages off
by more than 5% ?

PSU stays pretty cool. Should the voltages fluctuate at all? I ask
because they do move a very small bit.

3) Test things in sequence. Memtest86 for memory. Prime95 for CPU.
3DMark to cover the AGP slot and the video card (use demo mode
and use a copy of MBM5 to record temps and voltages while
the test runs). Using those tests, you may get some more symptoms
to work with.

Right now, I don't even have a floppy hooked up. I will do that
when I get home and run memtest, and prime95.

Generally, when a system shuts down, some hardware is trying to tell
you it is in trouble. If you insist on running the system in its
current state of discomfort, it will eventually fail, and sometimes
the damage caused can be expensive. Finish your testing as quickly
as possible, to reduce the risk of creating an expensive problem.

At least if something died, it would be easier to track the problem
down

I learned a lesson similar to this with a hard drive. I could hear
sounds like something was wrong with the head or actuator, but
said to myself "I'm too tired to do a backup tonight - I'll do
it tomorrow". Of course, when tomorrow came, the disk was dead.

There was a poster here, who had the "AGP warn" LED light on the
motherboard, indicating he was using an incompatible video card.
He said "I must have pressed the power button 50 times, until it
started". Of course, the incompatible AGP voltage fried the system.
If what is happening to you is a protection mechanism cutting in,
the form of protection might not be bullet proof enough to use
forever.

I've read somewhere that this mobo has the option to reboot on error,
or halt and show a blue screen. I looked last night and couldn't find
this setting was. If it would be possible to get a blue screen, at
least it would narrow where to look for the error. Was this only in
the prev revision, or is this included in a bios update?

I take it, as this is an Nforce2 board, that the CPU and RAM are
running at the same speed ("100%") ? The Nforce2 works best if
the CPU and RAM work in sync - otherwise you may find memory errors
crop up in memtest86.

I'm not sure what this means. It is an NForce2 mobo and the cpu is
running at 12.5V with a FSB of 166 . I have the RAM speed set to auto
right now. If I try to run the FSB at 200, the memory fails on
startup, 166 seems to be fine (or at least has been for the past four
months). I did set it to manual and tried to increase the latency to
3.0 from 2.5, but there was no change, so I reset it to auto.

HTH,
Paul

Thanks for the input,
Mat

 

[Mathew Duafala]

A bad power switch would certainly explain the symptoms - so you have
likely answered your question (and worked around the problem).

Unfortunately no. That's what I'd hoped, then the machine rebooted on
me (unless both the reset and power switch are bad). Maybe I'll make
my own power switch just to check it.

Mat

 

[Paul]

1) Check temperatures, fan speeds, and voltages in the hardware
monitor.

All the fans turn on and seem to run at reasonable rates. I don't
know what the rpm is supposed to be for them, but they are all moving
a fair bit of air.

2) It could be the power supply. Does the PSU get hot to the touch,
as in too hot to keep a finger on it ? Are the voltages off
by more than 5% ?

PSU stays pretty cool. Should the voltages fluctuate at all? I ask
because they do move a very small bit.[/QUOTE]

A small bit is normal. A PC PSU doesn't regulate that tightly on
all outputs. If you look at the ATX 20 pin cable harness, a +3.3V
pin has two wires leading to it, and the thinner wire is for feedback
about the voltage. The +3.3V should have the best behavior, but the
other voltages are defined by the turns ratio of the output transformer
and vary a bit with the load. (Most PSUs cannot adjust the outputs
truely independently of one another.)

The Vcore used by the processor varies as well, and this is called
"droop". It is due to the ohmic loss in the copper plane used to
distribute Vcore, and usually the regulator circuit boosts the
voltage a bit as a function of the current being drawn by the circuit.
That is called droop compensation.

Right now, I don't even have a floppy hooked up. I will do that
when I get home and run memtest, and prime95.

I've read somewhere that this mobo has the option to reboot on error,
or halt and show a blue screen. I looked last night and couldn't find
this setting was. If it would be possible to get a blue screen, at
least it would narrow where to look for the error. Was this only in
the prev revision, or is this included in a bios update?

That will be an option in Windows. Setting it to BSOD is useful
if the Event Log isn't getting any entries.

I'm not sure what this means. It is an NForce2 mobo and the cpu is
running at 12.5V with a FSB of 166 . I have the RAM speed set to auto
right now. If I try to run the FSB at 200, the memory fails on
startup, 166 seems to be fine (or at least has been for the past four
months). I did set it to manual and tried to increase the latency to
3.0 from 2.5, but there was no change, so I reset it to auto.


Thanks for the input,
Mat

I guess auto sets the FSB to the same speed as the memory, i.e.
166MHz FSB equals 166MHz Memory, and 166MHz*2 = DDR333.

When you run Prime95, maybe that will help identify whether your
power supply is the weak link. Watch the processor temperature with
MBM5 or Asus Probe (but don't install both at the same time).

HTH,
Paul

 

[Mark McNally]

I have a homebuilt system with the following.
Asus A7N8X mobo (rev 2.0)
athlon XP barton 2800
2 512 PC3200 samsung Ram chips
ATI Radeon 9600 All in Wonder

After running the computer fine for about 4 months, I am now getting
random reboots and shutdowns. When the machine shutsdown without
rebooting, it leaves the power LED on and it won't restart until I
unplug it and let it sit for about 10 seconds. Then I can plug it
back in and reboot.

I am pulling my hair out trying to track it down. The things I have
tried

-resetting the bios (which drops the FSB to 133 from 166)
-lowering the RAM speed
-disabling the onboard LAN and SCSI devices
-Checked the power supply (both with a multi meter and with asus
probe)

After having the system for about a month I overclocked it to 3Ghz for
a couple of days (Didn't really notice a difference so I reset it).
It was stable while overclocked (ie I burned it in).

I had a similar problem to this. I tested it with a different power
supply and my stability problems and shutdowns (actually, I lost monitor
sync, the power led stayed on - so I don't really think the machine
shut down) went away. It was a kicker really. At first my machine was
unstable at 166Mhz bus speed (running Prime95 on torture test for 2
seconds would cause my machine to "shutdown"). Then a month later, the
same behavior at 133Mhz bus speed (I didn't have time to fiddle with
it). It's back to normal although the CPU is running hot (I probably
put on too much heatsink compound during my fiddling process).

Mark

 

[Tim]

Checked your capacitors? (I don't think A7N8X has ever had this problem).

- Tim

 

[notritenoteri]

how up to date is your virus protection?

I had a similar problem to this. I tested it with a different power
supply and my stability problems and shutdowns (actually, I lost monitor
sync, the power led stayed on - so I don't really think the machine
shut down) went away. It was a kicker really. At first my machine was
unstable at 166Mhz bus speed (running Prime95 on torture test for 2
seconds would cause my machine to "shutdown"). Then a month later, the
same behavior at 133Mhz bus speed (I didn't have time to fiddle with
it). It's back to normal although the CPU is running hot (I probably
put on too much heatsink compound during my fiddling process).

Mark

 

[Mark McNally]

how up to date is your virus protection?

Pretty up-to-date. I use trend micro and I ran a test last night after
having installed a new power supply. Everything works great and no
viruses.

 

[Mark McNally]

Checked your capacitors? (I don't think A7N8X has ever had this problem).

No. How does one do this?

Mark

 

[Paul]

No. How does one do this?

Mark

Electrolytic capacitors use a wet electrolyte. If the electrolyte
breaks down, the inside of the capacitor can become pressurized.
A reverse biased electrolytic will explode like a fire cracker,
filling the air with black confetti if this pressure isn't
relieved. (That is a favorite prank in electronics labs, reversing
the polarity of someone's electrolytic cap on a breadboard. It
is also dangerous.)

In a motherboard application, the capacitors degrade more slowly.
The top of the capacitor (tall aluminum cylinder with thermoplastic
shrink sleeve) has a K or X stamped in it, and the stamping makes
a perforation for a safety pressure release. (I.e. If it has to
open due to pressure, it isn't supposed to go off like a
firecracker.) To check the capacitor, you look at the top of it.
The top should be flat. If the top is domed, that means there is
pressure in there. The capacitor is drying out, and will eventually
offer an ineffective capacitance to the circuit. Symptoms are,
the need to reduce the FSB to get the processor to remain stable,
or the motherboard will alarm due to Vcore going out of spec.

A second thing to look for, is a brown stain or puddle underneath
where the capacitor is soldered to the board. The brown color is
the escaping electrolyte.

Usually a cluster of caps is used, to share the strain from the
switching application. When one cap fails, the burden is carried
by the remaining caps, which accelerates their failure rate.
What this means, is when one cap starts to "dome", the others
follow in a matter of weeks or days.

Electrolytic capacitors fail with old age, and should last for
ten years or so, under mild temperature conditions. There was a
period of time, where some defective capacitors were made with
bad electrolyte formulation, and some motherboard brands like
Abit were hard hit. Asus for the most part, doesn't seem to have
bought any of those brands of caps.

Other Vcore circuit malfunctions, are a MOSFET failure. That
is a device with three legs, and a tab that is soldered to the
motherboard to enhance cooling. If one of those fails in the
ON state, the MOSFET conducts a lot of power from +12V, through
one of the toroid inductors, which frequently burns the MOSFET
and burns up the toroid as well. That, of course, will prevent
the motherboard from POSTing instantly.

HTH,
Paul

 

[Ken]

Electrolytic capacitors fail with old age, and should last for
ten years or so, under mild temperature conditions. There was a
period of time, where some defective capacitors were made with
bad electrolyte formulation, and some motherboard brands like
Abit were hard hit. Asus for the most part, doesn't seem to have
bought any of those brands of caps.

Here some info
http://www.pcmag.com/article2/0,4149,933571,00.asp
http://www.niccomp.com/taiwanlowesr.htm
http://www.overclockers.com/tips00140/
http://www.pcstats.com/articleview.cfm?articleID=195
http://www.reed-electronics.com/ele...=article&articleId=CA255062&rid=0&rme=0&cfd=1

 

[Mathew Duafala]

Well, I was convinced that the mobo was bad, so I bought another one
(the a7n8x-e deluxe) and a new cooler for the cpu. I swapped
everything out and just put the cpu, ram, and video card in. I still
can't even get it to beep (or do anything at all). The fans come on,
and the on board led is lit up so I know that there is power there.

Could the CPU be fried? How would I tell? It didn't have any sort of
discoloration or scorch marks on it.

Mat

 

[JBM]

Well, I was convinced that the mobo was bad, so I bought another one
(the a7n8x-e deluxe) and a new cooler for the cpu. I swapped
everything out and just put the cpu, ram, and video card in. I still
can't even get it to beep (or do anything at all). The fans come on,
and the on board led is lit up so I know that there is power there.

Could the CPU be fried? How would I tell? It didn't have any sort of
discoloration or scorch marks on it.

Mat

Have you tried clearing the CMOS? Also if you
power the MB with no CPU installed and a speaker
attached to the sound output do you get a no CPU
installed error? You could try the same with memory.
Also When I had this problem I've had the hearsink
turned 180 degrees from the correct position.

Jim M

 

[Max]

Have you tried clearing the CMOS? Also if you
power the MB with no CPU installed and a speaker
attached to the sound output do you get a no CPU
installed error? You could try the same with memory.
Also When I had this problem I've had the hearsink
turned 180 degrees from the correct position.

Jim M

I have this same problem and have the board wrapped up to return. But
Jim, you say the heatsink can be 180 degrees wrong - does that really
matter? I have the plastic screwdriver slot on the outside (near board
edge) which is the easiest place to finally secure the (AMD) heatsink.

And, if a CPU still heats up, is that a sign that it is OK?

Max

 

[JBM]

I have this same problem and have the board wrapped up to return. But
Jim, you say the heatsink can be 180 degrees wrong - does that really
matter? I have the plastic screwdriver slot on the outside (near board
edge) which is the easiest place to finally secure the (AMD) heatsink.

And, if a CPU still heats up, is that a sign that it is OK?

Max

The heatsink I use and most I've used has a recessed edge
That has to be aligned with the raised edge of the socket.
If it isn't the heatink doesn't set square on the CPU.

The CPU heating up means its drawing power not that
it's necessarily good.

Jim M