no signal

[Alex]

Hi everybody,
When I switch on my pc, on the monitor appears the message:"no signal". It
doesn't read the BIOS, this message appears immediatly. I've already tryed
the video card, the HD, the monitor, and all the cables in another PC, end
they work. So, now I think that the problem is on the mother board, or the
processor.
Could someone help me in order to understand exactly where is the problem?
Than you very much
Alex

 

[kony]

Hi everybody,
When I switch on my pc, on the monitor appears the message:"no signal". It
doesn't read the BIOS, this message appears immediatly. I've already tryed
the video card, the HD, the monitor, and all the cables in another PC, end
they work. So, now I think that the problem is on the mother board, or the
processor.

This just (usuallly) means the system failed to initialize
and post at all. When in this state are the fans spinning
or any LEDs lit, HDDs spinning, and/or any other signs of
electrical life?

A good first step would be unplugging PSU from AC for a few
minutes, then if that doesn't help unplug it again and use
the motherboard clear CMOS jumper.

Had anything changed recently in the system, had you been
inside or had it been moved from one location to another?

Inspect the system for failed capacitors, especially on
motherboard, and if you have a multimeter you might take
readings of the PSU voltages.

Could someone help me in order to understand exactly where is the problem?
Than you very much

Unless your CPU heatsink fell off or the fan failed it's not
likely to be the problem. PSU is a more common problem and
motherboard 2nd. Providing more details might help narrow
it down some including makes and models of all major parts
or at least PSU, motherboard, video, and a general idea of
the total system load like # of hard drives or anything
else using significant power.

 

[VanguardLH]

Hi everybody,
When I switch on my pc, on the monitor appears the message:"no
signal". It doesn't read the BIOS, this message appears immediatly.
I've already tryed the video card, the HD, the monitor, and all the
cables in another PC, end they work. So, now I think that the
problem is on the mother board, or the processor.
Could someone help me in order to understand exactly where is the
problem?

Even with no signal displayed on the monitor, you should still be able
to walk through the menus using the monitor's OSD (on-screen display).
Go pick the other input. You give absolutely NO INFORMATION as to
what monitor you have. If it is an LCD then maybe it has 2 inputs:
one analog and one digital. Maybe you have the wrong input selected
(and the monitor doesn't auto-detect which is inuse or you told the
monitor to not use auto-detect and only look at one input and picked
the wrong one).

So did you ever hear the POST (power-on self-test) beep?
Do you hear the fans spinning?
Hear the hard disk(s) spin up when you power up?
How do YOU know that the computer has power from the wall outlet?
How do YOU know that the computer's power supply came up?

 

[Alex]

Ok , till 2 hours ago, the hdd led remained fixed with the red light, an the
power led too. I've already tried the digital and analogic imput, with the
same bad result. I've a lcd monitor. I didn't hear the POST beep, and I
didn't hear the fans spinning, I only see the power led and the hdd led
switched but fixed, the hdd doesn't work. I thought that wasn't a PSU
problem.

NOW, I've tried the mother board in another PC and it doesn't start even the
power led is dead. Than I've put the old mother board in my PC and it works,
I,ve put the
Presumably faulty mother board in the the faulty Pc and it is completely
dead.

At this point I think that the problem is the mother board, and don't the
processor.
What do you think?
Thank you for your help

Alex

 

[kony]

Ok , till 2 hours ago, the hdd led remained fixed with the red light, an the
power led too. I've already tried the digital and analogic imput, with the
same bad result. I've a lcd monitor. I didn't hear the POST beep, and I
didn't hear the fans spinning, I only see the power led and the hdd led
switched but fixed, the hdd doesn't work. I thought that wasn't a PSU
problem.

NOW, I've tried the mother board in another PC and it doesn't start even the
power led is dead. Than I've put the old mother board in my PC and it works,
I,ve put the
Presumably faulty mother board in the the faulty Pc and it is completely
dead.

At this point I think that the problem is the mother board, and don't the
processor.
What do you think?
Thank you for your help

yes it seems likely the motherboard is the problem, although
if the two systems & motherboards+connected_parts have
different power consumptions, it could cause a progressively
failing PSU to still be able to power one within acceptible
running margin and not the other - but for now unless you
are able to test these PSU independant of the board, at the
required load, replacing the board seems the most logical
step. It wouldn't hurt to buy the replacement from
someplace with a good return policy just in case that
doesn't resolve the problem.

 

[VanguardLH]

Ok , till 2 hours ago, the hdd led remained fixed with the red
light, an the
power led too. I've already tried the digital and analogic imput,
with the
same bad result. I've a lcd monitor. I didn't hear the POST beep,
and I
didn't hear the fans spinning, I only see the power led and the hdd
led
switched but fixed, the hdd doesn't work. I thought that wasn't a
PSU
problem.

NOW, I've tried the mother board in another PC and it doesn't start
even the
power led is dead. Than I've put the old mother board in my PC and
it works,
I,ve put the
Presumably faulty mother board in the the faulty Pc and it is
completely
dead.

At this point I think that the problem is the mother board, and
don't the
processor.
What do you think?
Thank you for your help

Alex

Do the fans start to spin for a second and then slow down to stop? Or
do the fans just jerk a bit on first power up but never even make one
full rotation? Or are they completely dead with absolutely no
movement when you power up?

If the BIOS detects an overheating CPU, it will shutoff the power
within a second. Is the heatsink on the CPU? Is the CPU fan spinning
(the BIOS will check its RPM and halt if it sees no rotation of the
CPU fan)? Is the CPU fan plugged into the correct 3-pin mobo header?
Did you remember to use thermal paste (a very light thin coating and
not gooped on) between the heatsink and CPU?

Have you yanked out all memory modules and tested with just one of
them plugged into the mobo (and then tested again with just one of the
other memory sticks)? You need to test under a minimal hardware
configuration: PSU, mobo, video card, 1 memory stick, 1 hard drive
(power only, no data cable).

What voltages do you see from the PSU when you power up? Is the
120/240V selector on the back of the PSU in the correct position for
your area?

Did you attach just one hard drive to the PSU, disconnect the PSU's
20/24-pin connector from the mobo, and shorted the PS-ON wire (green)
to a ground wire to see if the PSU powers up (the hard disk should
start spinning and the PSU's fan should spin)? The logic on the mobo
determines if the PSU will be allowed to power up. The PSU supplies a
5VSB (standby) voltage to the mobo to power this logic. The logic
decides whether or not to fully power up the PSU. By disconnecting
from the mobo and shorting PS-ON, you effectively enable the PSU as
the mobo would.

Does the mobo and PSU work okay if you do NOT put the mobo into the
case and instead have the mobo outside of the case? If that works,
you have a short to case ground in your mobo's installation. From
what I gather, you have one mobo that works in both hosts so all their
hardware works and it is the suspect mobo that won't work in either
host. Looks like the mobo is bad, or something installed into the
mobo (memory, video card, other daughtercard) is bad.

 

[DaveW]

It sounds like either the power supply unit or the motherboard have failed.
The easiest way to test this is to replace the PSU with a known working one.
If that does not fix it then it is most likely that the motherboard has
failed and needs to be replaced. You cannot repair a motherboard.