sporadic system problems

[Peter]

Hi! Recently I started having all kinds of problems with my homebuilt system
that worked fine for about 8 months. Here's my setup:

MB: Asus P5B Deluxe
CPU: Pentium Core 2 Duo 2.4GHz
RAM: 4 x CM2X1024-6400 (4GB)
2x74GB WD Raptor hard drives in RAID0 - OS is there
1x250GB WD hard drive
1x500GB WD hard drive
1x250GB WD external hard drive
Video Card: nVidia GeForce 7900GS 256MB
Sound Card: Creative Audigy 4

So, about a month ago the system stopped booting (I had the CPU overclocked
to 3GHz or so). Clearing CMOS every time was basically the only way to boot
it. I decided to upgrade BIOS, upgrade failed and totally killed the
motherboard. Later I read on ASUS forums that this had happened to everyone
who tried to upgrade BIOS in P5B Deluxe in Vista (the only way to do it was
through BIOS setup). I ordered exactly the same model, but even with the new
board these problems did not go away. At least I know that the motherboard
is not the problem.
The system now never starts up when I turn it on the first time. I am
getting blue screens, no POST at all, or Vista just hangs during startup.
It's always something different. Yesterday, for example, I had to clear CMOS
in order to finally load the OS. Once the system loads the first time, I can
reboot it however many times I want - no problems. Then, on the next day
problems start again. When I turned it on earlier today, the system began
turning off and on by itself. Then, it froze a couple of times in BIOS
setup, froze a few times on POST, and a few times on Vista password prompt.
In order to finally start up, I had to disconnect everything but the MB and
video card. Then, once I got into BIOS setup and it did not freeze, I
connected the hard drives and finally was able to boot up.

Can anyone help?

Thank you

 

[kony]

Hi! Recently I started having all kinds of problems with my homebuilt system
that worked fine for about 8 months. Here's my setup:

MB: Asus P5B Deluxe
CPU: Pentium Core 2 Duo 2.4GHz
RAM: 4 x CM2X1024-6400 (4GB)
2x74GB WD Raptor hard drives in RAID0 - OS is there
1x250GB WD hard drive
1x500GB WD hard drive
1x250GB WD external hard drive
Video Card: nVidia GeForce 7900GS 256MB
Sound Card: Creative Audigy 4

I'm amazed it ran at all without a power supply. ;-)

So, about a month ago the system stopped booting (I had the CPU overclocked
to 3GHz or so).

Had it ran o'c, no other settings changes then suddenly it
stopped booting at the same speed it had previously? If so,
it would seem like a motherboard or PSU degradation occured
during that interval. You have a fairly beefy system, plus
o'c, I'd suspect the PSU first.

Clearing CMOS every time was basically the only way to boot
it.

So you clear CMOS, and presumably it then POSTs at the stock
speed, but do you then allow it to boot windows or do you go
into bios, save settings to the overclocked values... and if
you do, does it then resest and post ok or does that require
another bios reset if the o'c is attempted?

I decided to upgrade BIOS, upgrade failed and totally killed the
motherboard. Later I read on ASUS forums that this had happened to everyone
who tried to upgrade BIOS in P5B Deluxe in Vista (the only way to do it was
through BIOS setup).

I prefer using a boot disk (actually boot thumbdrive when
the system supports it, or boot Compact Flash card in a
CF-IDE adapter. Any windows SW flasher just adds another
layer of complexity that isn't needed, only has potential
bad effects, IMO.

I ordered exactly the same model, but even with the new
board these problems did not go away. At least I know that the motherboard
is not the problem.

Yes/no/maybe?

If the boards were made in the same lot with poor
manufacturing process or lots of some parts, it can effect
several of the same board, although I tend to agree the odds
are against it being the motherboard at this point.

The system now never starts up when I turn it on the first time. I am
getting blue screens, no POST at all, or Vista just hangs during startup.
It's always something different. Yesterday, for example, I had to clear CMOS
in order to finally load the OS. Once the system loads the first time, I can
reboot it however many times I want - no problems. Then, on the next day
problems start again. When I turned it on earlier today, the system began
turning off and on by itself. Then, it froze a couple of times in BIOS
setup, froze a few times on POST, and a few times on Vista password prompt.
In order to finally start up, I had to disconnect everything but the MB and
video card. Then, once I got into BIOS setup and it did not freeze, I
connected the hard drives and finally was able to boot up.

Can anyone help?

Thank you

I suspect you have failed capacitor(s) in your power supply.
You might unplug it for a few minutes then open and inspect
it, priimarily looking for vented caps around where the
exiting wiring harness leaves the PCB. If this is the
case, I suggest not running the system anymore even if it
can boot windows with default bios settings, as it may
further degrade and pose a risk to the motherboard, hard
drives, video card, etc.

 

[~misfit~]

Somewhere on the interweb "kony" typed:

I suspect you have failed capacitor(s) in your power supply.

I had that last week on one of my older machines. Scared the bejesus out of
me:

http://test.internet-webmaster.de/upload/1191392010.jpg

That's what it looked like after I plugged the PC in (with the side off and
my ear right next to the PSU). Went off like a shotgun. Luckilly I still had
my hand on the power cord, I unplugged it in about 0.002 sec. I found an
Enermax supply that had died a quiter death a while back that had a pair of
Rubycon caps in it the same size and specs as this and the one next to it. I
replaced them both and the PSU is running fine again.

[Warning: There can be dangerous voltages present acroos the bigger caps
like these even if your PSU has been turned off for a while. (mine sparked
against the soldering iron) I don't recommend that you open PSUs yourself
ubless you know what you're doing]

I know that's not exactly what you mean by failed capacitors Kony but I had
to share.

 

[Peter]

Sorry I forgot to mention the PSU. It's a Thermaltake W0104RU Toughpower
650W Power Supply w/Active PFC.

Thanks

 

[kony]

Somewhere on the interweb "kony" typed:




I had that last week on one of my older machines. Scared the bejesus out of
me:

http://test.internet-webmaster.de/upload/1191392010.jpg

Unless the fan fails, I seldom see those high-side caps
fail, it's almost always the ones after the transformer
output is rectified in the LC circuits, either the 3.3/5/12V
rails or the 5VSB.

That's what it looked like after I plugged the PC in (with the side off and
my ear right next to the PSU). Went off like a shotgun. Luckilly I still had
my hand on the power cord, I unplugged it in about 0.002 sec. I found an
Enermax supply that had died a quiter death a while back that had a pair of
Rubycon caps in it the same size and specs as this and the one next to it. I
replaced them both and the PSU is running fine again.

[Warning: There can be dangerous voltages present acroos the bigger caps
like these even if your PSU has been turned off for a while. (mine sparked
against the soldering iron) I don't recommend that you open PSUs yourself
ubless you know what you're doing]

I know that's not exactly what you mean by failed capacitors Kony but I had
to share.

Normally the PSU 5VSB and some parallel resistors drain
those caps down to a negligable level. I'm wondering if you
either had (have) another fault still, or if the remaining
voltage on the caps was low enough to be safe, even if a bit
startling.

Certainly if a high voltage cap fails it has to be replaced,
but the more common failures are the caps around the
existing wiring harness connection to the PCB, or (still in
the same general vicinity on the PCB) one set of inductors
before that point.

 

[~misfit~]

Somewhere on the interweb "kony" typed:

Unless the fan fails, I seldom see those high-side caps
fail, it's almost always the ones after the transformer
output is rectified in the LC circuits, either the 3.3/5/12V
rails or the 5VSB.

I knew those were the caps you were talking about, just wanted to share my
explosive experience. So you've never seen those big ones fail? Maybe it's
something to do with the fact that we have 220V mains in NZ? You're in the
US are you not? 110V mains. /Most/ supplies I've seen are switchable so,
when used with half the cap's rated voltage are probably less likely to
fail. The fan was/is working fine.

That's what it looked like after I plugged the PC in (with the side
off and my ear right next to the PSU). Went off like a shotgun.
Luckilly I still had my hand on the power cord, I unplugged it in
about 0.002 sec. I found an Enermax supply that had died a quieter
death a while back that had a pair of Rubycon caps in it the same
size and specs as this and the one next to it. I replaced them both
and the PSU is running fine again.

[Warning: There can be dangerous voltages present acroos the bigger
caps like these even if your PSU has been turned off for a while.
(mine sparked against the soldering iron) I don't recommend that
you open PSUs yourself unless you know what you're doing]

I know that's not exactly what you mean by failed capacitors Kony
but I had to share.

Normally the PSU 5VSB and some parallel resistors drain
those caps down to a negligable level. I'm wondering if you
either had (have) another fault still, or if the remaining
voltage on the caps was low enough to be safe, even if a bit
startling.

I hope the latter. It was only a small spark. However, I've heard others
issue warnings about dangerous voltages being retained in PSU caps so
thought I'd mention it.

Certainly if a high voltage cap fails it has to be replaced,
but the more common failures are the caps around the
existing wiring harness connection to the PCB, or (still in
the same general vicinity on the PCB) one set of inductors
before that point.

Yeah, I've heard that. Strangely, I've never had it happen myself. <touches
wood>

Cheers,

 

[kony]

Somewhere on the interweb "kony" typed:

I knew those were the caps you were talking about, just wanted to share my
explosive experience. So you've never seen those big ones fail? Maybe it's
something to do with the fact that we have 220V mains in NZ? You're in the
US are you not? 110V mains. /Most/ supplies I've seen are switchable so,
when used with half the cap's rated voltage are probably less likely to
fail. The fan was/is working fine.

Certainly any part is subject to a certain % failure rate,
but yes in the US we have 110V and in a PSU with voltage
doubling circuit, there are 200V caps leaving a 400V/340V
margin. On active PFC units, there should be same margin
regardless of input (so long as within spec'd tolerance).
I think it most likely you just came upon a defective cap,
or an extreme surge on the mains AC line.

I hope the latter. It was only a small spark. However, I've heard others
issue warnings about dangerous voltages being retained in PSU caps so
thought I'd mention it.

I've heard them as well, but they never give specifics of
the circuit, so given that _all_ of those I've seen have
both the resistors and 5VSB sub-supply operating to drain
them to a far lower level, I wait for an example of one that
does't before presuming the voltage would remain high
enough to matter.

Even if a cap is completely unloaded, it will drain down
to a level where the retained capacity vs voltage may be
startling, but in caps of this volume, it does't take long
for them to drain to a safe level, besides that there are
two mechanisms for further discharge in an ATX PSU.

Yeah, I've heard that. Strangely, I've never had it happen myself. <touches
wood>

You are either very fortunate, or avoid buying junk PSU.
Those last couple of stages output caps are pretty
common failure points in PSU powering modern systems. When
I first see signs of instability in a system formerly
working alright, the first thing I do is pull the PSU,
swapping in one known functioning properly, and examine it.
Over 1/2 the time, the PSU has failed caps in this scenario.

I should mention, this is mostly with original stock PSU.
I care not about warranty and immediately open a PSU to
inspect. If there are marginal caps, I can replace
them and reuse them on less demanding electronics projects.

IMO, tiny performance gains over time are not as important
as having any given example running for as long as
possible. Some aren't in the same situation, but I have
found a lot of people who would gladly pay $200 for older
parts so long as they're reliable, guaranteed to last for
awhile.