basic power problem

[BrianBloodaxe]

How do you get a motherboard and an atx power supply to come to life?

I hope this is not too obvious a question. But basically I've never built a
pc before so I don't have any experience. I've fitted extra memory, drives
and cards but I've never built one from scratch.
Anyway here is the background info. Recently I acquired a pc that had died.
It wouldn't power up. There were no beeps or fan activity from the power
supply unit.
The computer uses a standard atx power supply and motherboard. It was taken
to a pc repair shop and they tried it with a new power supply, which didn't
work, so they concluded there was a deeper problem.
Anyway I bought a new power supply and tested it with the new one, but
nothing happened. I had the same problem. However the fan on the power
supply came on very briefly (1 sec) then all activity would stop.
To make sure the switch on the pc wasn't faulty I shorted the power jumper
and nothing happened. So I thought the motherboard must be faulty.

I bought a cheap similar motherboard off eBay and I cant get this one to
work wither.

My question is If you have got say just a motherboard and an atx power
supply and nothing else, no hard drive, memory cpu etc. When you connect the
power supply to the atx power socket on the motherboard should the power
supply come to life with the fan spinning if the power connector jumper is
connected to a switch on the front of a pc case?

The motherboard I bought is a 'Gigabyte' GA-6WMM series Intel 810 AGPset. If
that means anything. I placed it on a table (with nothing connected to it)
and connected the power supply to it. Nothing happened (as would be
expected) however I looked through the manual and found the PW(Soft Power
Connector) jumper. Am I right in thinking this should connect to the pc
switch?
I shorted this with a screwdriver to simulate a switch action. But nothing
happened. (I was very disappointed).
I then attached various things (cpu memory, pci cards) and placed the
motherboard in the old computer case and connected the switch connector to
the PW jumper. But again nothing.
Have I missed something. If you were building a pc from scratch and had just
bought a motherboard (as i had) how would you tell if the motherboard was ok
before assembling the entire thing?
Thanks

 

[Chris Stolworthy]

How do you get a motherboard and an atx power supply to come to life?

I hope this is not too obvious a question. But basically I've never built a
pc before so I don't have any experience. I've fitted extra memory, drives
and cards but I've never built one from scratch.
Anyway here is the background info. Recently I acquired a pc that had died.
It wouldn't power up. There were no beeps or fan activity from the power
supply unit.
The computer uses a standard atx power supply and motherboard. It was taken
to a pc repair shop and they tried it with a new power supply, which didn't
work, so they concluded there was a deeper problem.
Anyway I bought a new power supply and tested it with the new one, but
nothing happened. I had the same problem. However the fan on the power
supply came on very briefly (1 sec) then all activity would stop.
To make sure the switch on the pc wasn't faulty I shorted the power jumper
and nothing happened. So I thought the motherboard must be faulty.

I bought a cheap similar motherboard off eBay and I cant get this one to
work wither.

My question is If you have got say just a motherboard and an atx power
supply and nothing else, no hard drive, memory cpu etc. When you connect the
power supply to the atx power socket on the motherboard should the power
supply come to life with the fan spinning if the power connector jumper is
connected to a switch on the front of a pc case?

The motherboard I bought is a 'Gigabyte' GA-6WMM series Intel 810 AGPset. If
that means anything. I placed it on a table (with nothing connected to it)
and connected the power supply to it. Nothing happened (as would be
expected) however I looked through the manual and found the PW(Soft Power
Connector) jumper. Am I right in thinking this should connect to the pc
switch?
I shorted this with a screwdriver to simulate a switch action. But nothing
happened. (I was very disappointed).
I then attached various things (cpu memory, pci cards) and placed the
motherboard in the old computer case and connected the switch connector to
the PW jumper. But again nothing.
Have I missed something. If you were building a pc from scratch and had just
bought a motherboard (as i had) how would you tell if the motherboard was ok
before assembling the entire thing?
Thanks

my first inclination would be to shunt the PSU to make sure it works
properly...cqan't rememre off hand which pins it is you need to shunt tho...
Then if PSU works I would try mobo with CPU and 1 stick of good ram ONLY!
Make sure the heatsink is installed the proper direction, (alot of people
install it backwards which can cause POST issues) try cleaning thermal
grease from CPU, and reapplying a thin layer. See if that breathes any life
into your sys...

 

[Pen]

Did you jump pins 14 and 15, which is power on
with just a known good drive as load?

 

[Mike Walsh]

Probably not. There is a wire that goes to the power supply that must be grounded to keep the power supply running. I don't believe that will be active without a CPU. With a CPU installed the power should stay on an you should get a beep code for no memory.

My question is If you have got say just a motherboard and an atx power
supply and nothing else, no hard drive, memory cpu etc. When you connect the
power supply to the atx power socket on the motherboard should the power
supply come to life with the fan spinning if the power connector jumper is
connected to a switch on the front of a pc case?

--

When replying by Email include NewSGrouP (case sensitive) in Subject

Mike Walsh
West Palm Beach, Florida, U.S.A.

 

[BrianBloodaxe]

Probably not. There is a wire that goes to the power supply that must be

grounded to keep the power supply running. I don't believe that will be
active without a CPU. With a CPU installed the power should stay on an you
should get a beep code for no memory.

--

When replying by Email include NewSGrouP (case sensitive) in Subject

Mike Walsh
West Palm Beach, Florida, U.S.A.

I shorted sockets 14 and 15 on the power supply unit and it comes to life.
So that seems to be okay.

'I don't believe that will be active without a CPU. With
a CPU installed the power should stay on an you should get a beep code for
no memory.
'

Is this true. Does the processor have to be attached to the motherboard for
the power supply to be switched on. I thought that it didn't. I thought you
could connect a good empty motherboard to an atx power supply, then short
the power switch connectors on the board, and the fan would start up on the
power supply.
Anyway I attached a processor and tried it again but nothing happened.
Does it look as if this new motherboard is faulty? I got it off ebay so I
suppose I have to write it off to experience.

 

[Pen]

The mobo has circuitry to keep the on line low, but that is
dependant on the power good line, so the only reliable
test is with a cpu or by shorting out the on pins at the
connector.

 

[BrianBloodaxe]

grounded to keep the power supply running. I don't believe that will be
active without a CPU. With a CPU installed the power should stay on an you
should get a beep code for no memory. connect jumper



I shorted sockets 14 and 15 on the power supply unit and it comes to life.
So that seems to be okay.

'I don't believe that will be active without a CPU. With
a CPU installed the power should stay on an you should get a beep code for
no memory.
'

Is this true. Does the processor have to be attached to the motherboard for
the power supply to be switched on. I thought that it didn't. I thought you
could connect a good empty motherboard to an atx power supply, then short
the power switch connectors on the board, and the fan would start up on the
power supply.
Anyway I attached a processor and tried it again but nothing happened.
Does it look as if this new motherboard is faulty? I got it off ebay so I
suppose I have to write it off to experience.

I've just read that this problem may be caused by a fault with the power
supply connector that attaches to the motherboard. I've noticed that there
is no Pin 18 http://www.jeae.dk/Computere/atx_-_psu.htm It is empty on my
power supply. Might this be the cause?

 

[Pen]

Pin 18 is the -5V line, and most recent boards don't use it.
Unlikely it would affect any board from turning on as it's
not part of the power good signal anyway.

 

[~misfit~]

Pin 18 is the -5V line, and most recent boards don't use it.
Unlikely it would affect any board from turning on as it's
not part of the power good signal anyway.

The GA-6WMM is not a 'recent' board. It's about five years old.

 

[kony]

On Fri, 23 Jul 2004 17:59:20 +0100, "BrianBloodaxe"

Is this true. Does the processor have to be attached to the motherboard for
the power supply to be switched on. I thought that it didn't. I thought you
could connect a good empty motherboard to an atx power supply, then short
the power switch connectors on the board, and the fan would start up on the
power supply.
Anyway I attached a processor and tried it again but nothing happened.
Does it look as if this new motherboard is faulty? I got it off ebay so I
suppose I have to write it off to experience.

The average motherboard from that era did not need a CPU
installed to turn on the power supply, but some did... I do
recall Compaq i810 chipset motherboards that did require CPU
installed.

However, eBay certainly is another variable, the board bought
there may indeed be dead. I'm assuming the parts you're trying
were all original, or at least did once work together. In other
words, you're not trying to use a Coppermine Celeron on a board
only capable of supporting older Celerons, or high-density memory
since 810 chipset doesn't support it.

 

[Pen]

And your point is? Even when used it served a very limited
purpose, and was always very low power.

 

[kony]

I've just read that this problem may be caused by a fault with the power
supply connector that attaches to the motherboard. I've noticed that there
is no Pin 18 http://www.jeae.dk/Computere/atx_-_psu.htm It is empty on my
power supply. Might this be the cause?

No, your board doesn't need it.
You shorted the original power supply's PS-On pin to ground (with
a load like a drive attached) and it turned on and ran, right?
If so, since this was the original PSU that had formerly ran the
system, we can assume motherboard needed nothing more than it
provided.

If you have a multimeter it would be good to check voltage levels
when PSU is running.

 

[kony]

How do you get a motherboard and an atx power supply to come to life?

Depneds on the motherboard... with some it's easier to disconnect
power supply and ground the PS-On signal while it has a load on
5V rail (like a worthless hard drive plugged into connector, or
at least risking a device as low-value as possible if you suspect
PSU is problematic).

Anyway here is the background info. Recently I acquired a pc that had died.
It wouldn't power up. There were no beeps or fan activity from the power
supply unit.

So system was left in this state?
First thing I'd check is basics like, is the power supply fan
turning freely (if you stick a staw in and give the blades a
littel push, while UNPLUGGED from AC of course).

Also examine motherboard for failed capacitors, domed leaky
reside, etc.

Also try clearing CMOS, but that's more often a resolution
associated with rebuilds, new builds, not systems that were
running and left in present configuration.

The computer uses a standard atx power supply and motherboard. It was taken
to a pc repair shop and they tried it with a new power supply, which didn't
work, so they concluded there was a deeper problem.

What motherboard?
A concise list of major components is always a good start.

Anyway I bought a new power supply and tested it with the new one, but
nothing happened. I had the same problem. However the fan on the power
supply came on very briefly (1 sec) then all activity would stop.
To make sure the switch on the pc wasn't faulty I shorted the power jumper
and nothing happened. So I thought the motherboard must be faulty.

.... or something is shorting out, or other unforseen problem with
device connected to power supply. To rule out other devices the
system can be stripped down to only minimal components, CPU, 1
memory module (2 if they're RIMMs), and video card. Substitute
different video card if possible. Substitute different CPU if
heatsink was dislodged or fan is seized or unplugged, etc.

I bought a cheap similar motherboard off eBay and I cant get this one to
work wither.

Beware of cheap-off-eBay parts... who knows if it works?

My question is If you have got say just a motherboard and an atx power
supply and nothing else, no hard drive, memory cpu etc. When you connect the
power supply to the atx power socket on the motherboard should the power
supply come to life with the fan spinning if the power connector jumper is
connected to a switch on the front of a pc case?

Often it will come on, stay on, but some motherboards won't keep
it on (some Compaqs are memorable) if there's no (or incorrect,
not supported) CPU in the socket). Don't recall about memory on
those Compaqs but a "typical" non-OEM motherboard will keep PSU
on with nothing else connected or installed on board.

The motherboard I bought is a 'Gigabyte' GA-6WMM series Intel 810 AGPset. If
that means anything. I placed it on a table (with nothing connected to it)
and connected the power supply to it. Nothing happened (as would be
expected) however I looked through the manual and found the PW(Soft Power
Connector) jumper. Am I right in thinking this should connect to the pc
switch?

Yes, according to the manual that's Pin 6 & 8, they are the two
for the on switch connection. Shorting these two together should
turn on system, and it sounds like you had correct pins since the
PSU fan did momentarily turn, which it wouldn't have if you had
wrong pins.

I shorted this with a screwdriver to simulate a switch action. But nothing
happened. (I was very disappointed).
I then attached various things (cpu memory, pci cards) and placed the
motherboard in the old computer case and connected the switch connector to
the PW jumper. But again nothing.

Now I am confused, you previously mentioned that fan did turn,
but now you report "nothing".

Are you certain system is in original configuration that it was
in when working? You might try the memory in the other slot.

Have I missed something. If you were building a pc from scratch and had just
bought a motherboard (as i had) how would you tell if the motherboard was ok
before assembling the entire thing?

I'd try it on a bench (table, etc) but not lying on an
anti-static bag. Known good memory and PSU would be connected,
and motherboard manual would be used to confirm CPU support.
Since that is a socket 370 board, the most compatible CPU would
be a Celeron 300-533, Mendocino. They are not green like a
Coppermine but dark brown with pins visible on top, like this:
http://www.informania-fr.com/overclocking/celeronpgga.jpg

If you have questions about the CPU working you might need try a
different one or try that CPU in another system.

I don't know how long it's taken you to do all this testing but
it seems a shame that you've bought the 2nd PSU and still it's
not working. If you want an 810 motherboard for free (just pay
shipping) post your email address and I"ll get back to you.

 

[BrianBloodaxe]

On Fri, 23 Jul 2004 17:59:20 +0100, "BrianBloodaxe"



The average motherboard from that era did not need a CPU
installed to turn on the power supply, but some did... I do
recall Compaq i810 chipset motherboards that did require CPU
installed.

However, eBay certainly is another variable, the board bought
there may indeed be dead. I'm assuming the parts you're trying
were all original, or at least did once work together. In other
words, you're not trying to use a Coppermine Celeron on a board
only capable of supporting older Celerons, or high-density memory
since 810 chipset doesn't support it.

The new motherboard I got off ebay came with a seperate PentiumIII
processor. I used this one. I'm not sure what type of memory I used. I just
took 2 sticks out off the dead computer and used those. They fitted in the
black DIMM slots okay.
When trying this new ebay motherboard, there is NO activity from the power
suppy fan. On the old motherboard in the orignal dead computer the fan would
at least try and come on briefly.

 

[kony]

On Sat, 24 Jul 2004 09:36:30 +0100, "BrianBloodaxe"

The new motherboard I got off ebay came with a seperate PentiumIII
processor. I used this one. I'm not sure what type of memory I used. I just
took 2 sticks out off the dead computer and used those. They fitted in the
black DIMM slots okay.
When trying this new ebay motherboard, there is NO activity from the power
suppy fan. On the old motherboard in the orignal dead computer the fan would
at least try and come on briefly.

Older socket 370 boards (like first revision or more of Intel 810
chipset) would allow fitting a socket 370 CPU in the socket but
system wouldn't even POST, could potentially produce symptoms you
saw, but only with the new CPU in the old board, not new CPU in
new board of course. Unless the heatsink fell off the old CPU,
or someone had made a gross error trying to overclock it, odds
are high that the CPU is fine and it's the motherboard that's the
problem, but it's a bit of a mystery why both boards aren't
working for you with multiple power supplies. You might just be
incredibly unlucky, it would help a lot if you'd had another
system working with compatible parts so you could test everything
by swapping parts.

If the board from ebay was new/unused it might have a plastic
insert under the battery or a clear-cmos jumper in the wrong
position to keep battery from draining. That still doens't
explain what's happening with the older board though, but along
those lines you might check the battery voltage and swap
batteries.

Higher-density memory would also fit in the slot of a board that
couldn't support it, but again since memory came from old board
it should at least work in that board, unless someone had just
thrown a bunch of parts together into a case and had never had it
working themselves before it was given to you. Also that memory
would work in the newer PIII motherboard, AFAIK there weren't any
socket 370 boards that suported coppermine (a socket 370 PIII
would be a coppermine) but not high-density memory. I'm not 100%
certain of that though, technically such a board "could" be made
but it doesn't seem to make sense that any manufacturer would do
so.

There's probably something I'm missing, it helps a lot to just
have a dead system in front of oneself as it can be more obvious
when something is wrong, but then even simple problems can go
overlooked due to very nature of their simplicity... It once took
me many hours to discover that a jumper was defective and only
had part of it's metal insert in it, though that is a relatively
rare problem, I'm not suggesting it's at all likely to be a
defective jumper.

Looking at it from odds though, odds are high that when a system
fails, the motherboard is the problem (that or the power supply)
and odds are also fair that if you were to find a place where a
dead board could be bought, eBay would be that place. A socket
370 CPU in an intel 810 chipset board is a relatively light load,
any functional 120W power supply can run that with typical
complimentary parts like a hard drive, optical, and modem, so
even a low-end junk generic power supply that couldn't begin to
power a high-end new system should have no trouble with that
light of a load (especially when you had all parts removed). Do
check the power supplys' rear AC voltage switch though (if they
have one, some don't), that it's set appropriate to AC input per
your location.

 

[Trent©]

When trying this new ebay motherboard, there is NO activity from the power
suppy fan. On the old motherboard in the orignal dead computer the fan would
at least try and come on briefly.

Does the PS work on ANY mb any longer? You may have blown the ps.



Have a nice week...

Trent©

NUDITY...birth control for folks over 50!

 

[kony]

Does the PS work on ANY mb any longer? You may have blown the ps.

Along that line of thinking, it should be noted that if board was
shorting out PSU, it may be necessary to unplug it from AC for a
minute to reset it, before it would come on again (that is, if
everything else where then conducive to system working).

 

[half_pint]

Basically I am just guessing but I think how things work is as
follows.

You power on, the PSU is designed to supply a limited amount
of power to the CPU.
The CPU used this power to start up and do some basic stuff
(not sure what really), then the CPU sensing everything is OK
sends a signal to PSU to 'come fully on-line' (fully power up).

I don't know if that is right or not but it sounds sensible as it
would prevent excessive damage being done to the circuitary.

I mean it would be a good fail safe for the CPU to initially have
to tell the PSU to be 'on', and perhaps for it to have to periodically
send the PSU a signal to keep it on. This would prevent excessive
damage, and perhaps electrical fires?

Anyway, just a guess.
It may have already been mentioned in the thread (just scanned it).

So I reckon you need a CPU and memory etc...

Such a mechanism would *probably* prevent futher damage if there
is a fault somewhere, either on the board, CPU or memory.

Anyway like I said, I am guessing so don't blame me!!!

Really the repair shop should have put your PSU in a working
computer not vice versa IMO.

I am a little confused with your post, do you know the CPU memory
ect... work?

I kind of get the feeling that (to use an Irish phrase) when giving
directions
"Well if I was you I wouldn't start off from here at all."

I would have started off testing the memory, then CPU in a working
system, then your populated motherboard, with a working PSU.

You seem to have started from a place where it is difficult to 'get anywhere
from'.

Anyway I have no experience of building or testing computers, but
things like shorting out a fail safe mechanism don't, on the face of
it, sound like a very clever idea.

half_pint <-------------- computer hardware novice.

 

[Eric]

You power on, the PSU is designed to supply a limited amount
of power to the CPU.
The CPU used this power to start up and do some basic stuff
(not sure what really), then the CPU sensing everything is OK
sends a signal to PSU to 'come fully on-line' (fully power up).

And the motherboard sends this signal to the PSU...how?

 

[BrianBloodaxe]

And the motherboard sends this signal to the PSU...how?

To recap
I had a computer that suddenly died. (ATX 5 year old PentiumIII one that
comes on a 'daughter board' with 2 sticks of 128MB memory on long black DIMM
connectors)This machine had worked pretty much ok for 5 years then one day
the computer wouldn't switch on, there was no fan activity on the power
supply, no beeps nothing, just silence)
It was taken to a pc shop. They said they tried a new power supply with it
that worked for a while but was then destroyed!!!! so they concluded there
was something very wrong with the system and it would cost allot to get it
repaired. So a new computer was bought and I was given this old computer to
see if I could do anything with it.
I tested the power supply by shorting pins 14 and 15 and got nothing. I took
the motherboard out with just memory and processor and put it on a desk and
had a look. There was no obvious damage. No melted components etc. I
connected the power supply to the motherboard and found the connector that
the front power switch connects to and shorted that with a screwdriver.
Nothing.

I was suspicious of the claim that the computer had destroyed a new power
supply so I then bought a cheap new power supply and tried that. But got
nothing. However I noticed that each time the computer is switched on with
the new psu the fan very briefly spins ( half second) then stops. I tested
the new power supply by shorting pins 14 and 15 and it came to life so it
works and was not destroyed by the computer.

I concluded that the motherboard must have a fault so I bought an old cheap
one off ebay.
When it arrived I unpacked it and placed it on a table, rather than fitting
it into the old computer case. I decided to test it by connecting the new
motherboard to the new power supply. This motherboard came with a PentiumIII
installed. So the new motherboard and processor, with nothing else attached
was connected to the power supply, and the power switch connectors were
shorted. But nothing happened. Nothing. At this stage I was very
disappointed. I thought that with a new (albeit second hand and bought off
ebay) motherboard and a new power supply. Both having nothing to do with the
dead computer. That at least this motherboard should work and cause the
power supply fan to come alive but I got nothing. The fan wouldn't even try
and come on a second as it had done with the original system.

I then installed the new motherboard into the old case, and connected
memory, pci cards and the hard drive and tried it. But nothing. I didn't
think it would as the motherboard hadn't worked earlier when I tested it.
So I posted to this group.
It looks like I've bought a dud motherboard. Or maybe I've done something
wrong..........
I don't have a spare working system to test the various components. But I
know the new power supply works and the hard drive and I think the memory
and original processor as the original computer just suddenly died out of
the blue. I would have though that if these components were failing there
would have been some signs like lockups and blue screens.