PC wont turn on after adding new cpu

#21

dave xnet wrote:

Quote:

On Mon, 21 May 2007 21:58:49 -0400, Paul <nospam (AT) needed (DOT) com> wrote:

dave xnet wrote:
On Mon, 21 May 2007 15:51:45 GMT, dave xnet
davexnet02DEL (AT) ETEyahoo (DOT) com> wrote:

Picked up the meter in Kmart.

Here's the results, machine off, after using shutdown in windows:
purple 5, green 5 grey 0

I waited 5 minutes and without touching any buttons, tested again,
purple 5, green 5, grey 0

Pressed the front power switch, green power LED lights but
machine does not power on. Got these voltages as fast as I could
(within about 30 seconds anyway)
purple 5, green 4.9 grey 0

I'm not sure if I full understood your instructions regarding the
"when" to test- if I should do more, please let me know.
Likewise, if you see a glaring problem already.
Thanks very much -
Dave H.
To help with the wire colors, you can get ATX power supply specs
from formfactors.org . The first two are for 20 pin supplies, and
will give you a historical perspective (i.e. what happened to pin 18).
The third one is for a 24 pin supply and is the most recent. You can
pick the spec that best matches what kind of supply you have.

http://web.archive.org/web/200304240...12V_PS_1_1.pdf
http://www.formfactors.org/developer...X12V_1_3dg.pdf

http://www.formfactors.org/developer...public_br2.pdf

The green wire is PS_ON# and when you push the front button, it should
drop from 5V to close to zero. Perhaps a value of 0.4V or so. That might
be a saturated transistor driving the line. So it appears the motherboard
is not sending PS_ON#.

So the question would be, what is gating (preventing) PS_ON# from going low ?
It is interesting that you say you "cycle the A.C." and the thing is then
startable. It implies that removing +5VSB and then making +5VSB available
again, is enough to clear the problem and allow PS_ON# to pass. A person
could blame the motherboard for this, except in situations where some
external influence upset the operation of the motherboard. I cannot
see the relationship between the new processor and old, which would
do this. (Unless the motherboard was mechanically damaged, or the
motherboard shifted and a mounting screw or standoff is shorting
something.)

One thing did happen during the course of the cpu transplant.
There are 4 or 5 capacitors in a row next to the heatsink/fan
The side of my hand accidentally applied a little pressure to the one
on the end of the row when I was negotiating with the HSF retaining
clips.
It seems so minor that I had all but dismissed it.
Perhaps I dislodged or loosened one of it''s connectrs
I can check it, but I'll have to remove the motherboard and look at
the back - perhaps resolder it.
The fact that your power LED comes on, on the front panel (?), says
the front panel LED is powered by +5VSB, and it also says that the
motherboard logic thinks it is driving PS_ON# active as well. In
other words, the decision to turn on the LED on the front of the
computer case, implies the motherboard also wanted the PS_ON# signal
to be active too.

In the spec, PS_ON# requires the motherboard driver to sink 1.6 milliamps.
Which is not really a lot of current, as drivers go. Pad drivers on logic
ICs, typically might have 8, 12, or 16mA drive, for general purpose I/O.
If there wasn't an open collector logic device available, Biostar could also
use a transistor, which could drive way more than that.

I downloaded the manual, and the section on "CPU overheat", describes
a function where the computer will not turn on - until the A.C. is
cycled. Maybe this is a "feature" ? (PDF page 20 - CRU51M9_0829C.pdf)
Again, it is a mystery as to why a change in processor, could lead
to this feature running amok.

http://www.biostar.com.tw/products/m...orce%206100-M9
http://www.biostar.com.tw/products/m...%206100-m9.exe
I saw this, it says either remove the power line or reset the cmos.
But is it safe to reset the CMOS while the power line is attached?
If not, surely one implies the other.
if it is I'll try this/
Just out of curiosity, what does the hardware monitor read for a CPU
temperature, when the motherboard does manage to run ? Is the temp
normal or is it out of whack (like 255C) ?
The items I've looked at to check temps are in the Bios PC Health
page.
Also a program called Aida32, which I think is an earlier version of
Everest. The idle temps are about 34C, while about 46 under load.
I've touched the side of the HSF it's generally cool to the touch.
It is certianly making contact with the processor.
I don't see the cpu overheating, perhaps the sensor is bad?
aida32 doesn't report this. What else can I check it with?

I don't have the necessary expertise, knowledge or experience to do
much more of this diagnosis that you and w_tom have suggested.

At this point, I'm getting ready to put back the old cpu and see if it
still occurs. If it does, at least then I'll know that either the
mobo or power supply is bad( I think)
However, what if I put in the old cpu and it's working
perfectly?
Paul

I think it is worthwhile to put the old processor back and
repeat the test. So you can see if the behavior stays or
leaves.

With the incident with the capacitor, you can break where the wire
connects to the capacitor, if you applied enough pressure. I doubt
you'd pull the solder loose. If you damaged the capacitor, the
most observable result would happen if the plates of the capacitor
shorted inside the cap. If the capacitor failed open circuit, chances
are you wouldn't see any effect. There are multiple capacitors on
the primary and secondary sides, and it is possible the circuit will
still work just the same (plus or minus a bit of ripple). I wouldn't
worry about it too much, unless you can visually see damage (like
one side lifted higher off the board than the other, implying something
broke inside the capacitor).

(Pictures of an electrolytic)
http://www.microphotonics.com/skysca...tronics_3.html

In the spirit of swapping stuff, if you get tired of this motherboard,
there are always others.

Paul

#22

On May 22, 1:39 am, dave xnet <davexnet02... (AT) ETEyahoo (DOT) com> wrote:

Quote:

I saw this, it says either remove the power line or reset the cmos.
But is it safe to reset the CMOS while the power line is attached?
If not, surely one implies the other.
if it is I'll try this/

All those other suspicions - loose capacitor next to CPU, excessive
heat, reset CMOS - all are not involved. Long before any of those can
create a problem ... first the power supply 'system' must establish
power.

Grey wire - also called "power good" - is the message to everything
to start working. No 'power good'? Then CMOS does nothing. Heat
never causes a problem. Voltage from that capacitor has no
functioning CPU to halt.

Long before anything happens, the power supply controller must order
its power supply ON. Only after power is stable and "power good"
signal created - only then does everything else start working.

Ignore all the 'try this and try that' speculation. Without those
voltages, then nothing else even tries to work. None of those other
functions hinders a 'power on' function. Your problem is best defined
by what happens on purple, green, gray, and power switch wires.
Nothing will work if those voltages fail.

#23

"dave xnet" <davexnet02DEL (AT) ETEyahoo (DOT) com> wrote

Quote:

On Tue, 22 May 2007 07:51:06 +1000, Franc Zabkar
fzabkar (AT) iinternode (DOT) on.net> wrote:

snip
When I shutdown windows and later on try to start the pc,
the only thing that happens is the power LED lights up.
No fan, HD or other activity.
Power supply is an Antec Truepower 430W.

,snip
What do you infer from this behavior?
Thanks,
Dave

I have startup issues with an Athlon XP 2500+ in an ECS L7S7A2
motherboard. My original PSU was a 200W fake claiming to be a 400W.
Replacing it with a 350W Antec left me with exactly the same problem.
:-(

I suspect that something in my motherboard's standby circuitry doesn't
get initialised properly. There are two rails, +5VSB and +3.3VSB. The
latter is generated on the motherboard. Maybe the +3.3VSB doesn't come
up fast enough ??? Note that my problem only occurs after the AC power
is cycled. Once the machine has powered up successfully, you can shut
it down from the front switch and restart it as many times as you like
... until you cycle the AC power again. Even then, the problem doesn't
always happen. When it does happen, I can nearly always get it to
start by powering off and on from the front switch. The reset switch
has no effect.

I suspect that there may be nothing wrong with your PSU. Instead it
could be the motherboard's standby circuitry that is at fault.

- Franc Zabkar
Thanks for the info Franc.
My case is slightly different; it occurred after I upgraded the cpu.
Some have said well perhaps the load increased, but both cpu's
consume 89W according to AMD.

Also, mine occurs when ever the PC is shutdown.
If I recycle my AC, it works first time.

I sent a message to Antec to see if they have any clues.

Also left a message with the CPU vendor, but haven't heard
from them yet
I have purchased a digital multimeter and I'm going to measure
the voltages as mentioned in an earlier post.
Dave

It always seems that most PSU failures for me have happened after I have
made some change in components and then power back up. There is really no
reason for it, it just seems to happen that way in my own experience. w_tom
is correct as far as taking voltage readings is concerned. The 'power on'
circuitry is where I have found most problems and if there is any problem
there, it is time to replace the PSU. Of course there could be a MB issue,
but I would definately look to the PSU as the first culprit. All your
symptoms seem to point in that direction.

Ed

#24

On 22 May 2007 03:27:03 -0700, w_tom <w_tom1 (AT) usa (DOT) net> wrote:

Quote:

On May 22, 1:39 am, dave xnet <davexnet02... (AT) ETEyahoo (DOT) com> wrote:
I saw this, it says either remove the power line or reset the cmos.
But is it safe to reset the CMOS while the power line is attached?
If not, surely one implies the other.
if it is I'll try this/

All those other suspicions - loose capacitor next to CPU, excessive
heat, reset CMOS - all are not involved. Long before any of those can
create a problem ... first the power supply 'system' must establish
power.

Grey wire - also called "power good" - is the message to everything
to start working. No 'power good'? Then CMOS does nothing. Heat
never causes a problem. Voltage from that capacitor has no
functioning CPU to halt.

Long before anything happens, the power supply controller must order
its power supply ON. Only after power is stable and "power good"
signal created - only then does everything else start working.

Ignore all the 'try this and try that' speculation. Without those
voltages, then nothing else even tries to work. None of those other
functions hinders a 'power on' function. Your problem is best defined
by what happens on purple, green, gray, and power switch wires.
Nothing will work if those voltages fail.

When the PC is shutdown from within windows and it closes down and
to all intents and purposes it looks as if you pulled the plug - but
it's not off is it?

For example, if I look at the back the nic lights are still flashing.
So some part of the motherboard is still receiving power.

Would you still expect the gray wire to still provide it's
*power ready* voltage when you press the button on the front?
I think I set my meter to 1 significant digit. It read 0,0 on the
gray and I thought this was the problem. Perhaps not?

I've started reading Scott Muellers information here:
http://www.informit.com/articles/art...p?p=31105&rl=1
It has a lot of info for somebody in learning mode.

appreciate your help -
Dave H.

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PC wont turn on after adding new cpu

Homebuilt PCs Building your PC from motherboards and cards (alt.comp.hardware.pc-homebuilt)

Re: PC wont turn on after adding new cpu - 05-22-2007 , 01:33 AM

Re: PC wont turn on after adding new cpu - 05-22-2007 , 05:27 AM

Re: PC wont turn on after adding new cpu - 05-22-2007 , 08:11 AM

Re: PC wont turn on after adding new cpu - 05-22-2007 , 11:15 AM