[SOLVED] Monitor doesn't turn on when I turn on the computer

[agmg]

I have a weird problem with my kids' desktop which I guess it is not software-related (or maybe it is?).

This computer is a custom built pc, about 4 years old. It has a Core2Duo@1,8GHz, 2GB DDR2 RAM, an ATI HD5570 Video Card (replaced a borked 7900GT) connected to a 22'' LG monitor through DVI, a WD 250GB hard disk and a 350W power supply from OCZ. I can supply detailed info if needed. It has PCLOS KDE 2012.08 installed on it and is working fine except for one issue I'm describing right below.

When I turn on the computer the monitor acts like it's not getting any signal and goes to stand-by mode. Only way I can get the monitor to turn on is this: press the power button of the tower constantly until it shuts down, disconnect both devices from the power supply, reconnect them after a couple of seconds and turn them back on. Computer works fine until next shutdown. When I try to turn it back on, same thing happens and same steps have to be followed for the monitor to turn on.

Things I have tried so far:
- My mainboard has an intergrated Intel Graphics Chipset (G965). I have tried connecting the monitor to this output, removing the ATI video card, still the same.
- I have tried both VGA and DVI connections (the monitor has both), still no luck.
- Tried with the bare minimum parts of the pc (only one memory module, no extra usb etc), nothing.
- Connected the monitor to my laptop and works fine between shutdowns and restarts.

Any ideas? I'm thinking that maybe it's the power supply unit but I'm not sure.
Could it be the battery of the mainboard that needs replacement?
Could it be something wrong in the shutdown procedure of the OS?

I appreciate any help given!

[µT6]

the psu is a bit small but not sure if it could had that effect

usually when a psu is too small you have weird restarts, shutdowns and the system works hotter than it should, for example the hard disk ends hotter and southbridge too

does the video card has a special power connector to the psu?  i assume it is a passively cooled low power consumption video card

when you enter bios, does it have signal?

[agmg]

Never had problems with the PSU so far, not at least like the ones you describe (weird restarts etc).
The previous card was much more power consuming than the new one. The 7900GT had an extra power connector and a huge fan -it was overclocked by the manufacturer- while the HD5570 has only a small standard fan and no extra power cable.

I can't get to BIOS when this happens, there is no signal at all to the monitor.
It's like the computer is turned on but dead. There are no weird beeps coming from the mainboard...
And if I leave it going, I doubt that it continues to boot normally as I don't come to hear the welcome sound of PCLOS.
It is set to auto-login so it would eventually come to the desktop if everything was OK...

[µT6]

what happened to the previous video card, the gt? that psu is probably the minimum recommended to run that video card

is it a mainboard with two pci express x16 slots?  how old is the mainboard? maybe check it if it is old and could have a damaged capacitor

also check the video card connector, probably doesn't have electrolytic capacitors so nothing to check on it

when this doesn't happen, can you get into bios?

have you changed any setting on bios?

i had cases where a system required a bios reset to work properly, can you try that?  remove cr2032 battery and reset bios and then put cr2032 battery again and configure bios again to see if it happens again

[agmg]

The mainboard is a Gigabyte GA-965G-DS3 and it has only one PCIx slot. The previous card started giving strange artifacts and many times resulted in system freezes. The new one was bought about a couple of months ago and was working fine until the last days. Same behaviour when I remove the card and use the built-in graphics chipset (which only has VGA output).

I tried different cables for DVI and also for VGA.
I did reset the BIOS by removing the battery for a few minutes and also using the two-pin jumper (Clear CMOS).
Maybe do another try and leave all settings to the default ones to see how it goes.

I'm suspecting either the PSU or the mainboard but I don't have any spare parts to test.
You don't think that the battery on the mainboard may cause such behaviour?

[µT6]

i am more inclined to the mainboard than he psu

you can ope the psu to see if there is damaged capacitors or anything weird going on, also a bit of cleaning won't do harm

[ThirdOfSix]

Are you sure that the monitor back light circuitry is not failing?

I would try a different monitor and or try that monitor on a different computer.

There is so much energy saving crap in the operation systems now that changing cards may have caused the system to do a complete shutdown on the monitor where it may have only been putting it into standby before.

The good thing is that if it is the monitor, so far the Samsung monitors I have worked on with that problem have responded well to just replacing the electrolytic capacitors.

My 20 inch hp monitors on the other hand use some convoluted circuitry that does not respond well to such a treatment and of course without connections, I can not get schematics for them.

One of the two is showing the early stages of failure so I never allow it to shutdown completely because it may never start again.

[agmg]

Thanks μT6 for all the suggestions.
I will give it a good clean and check and if it insists, then maybe Santa will bring a new mainboard as a Christmas gift for my kids

[agmg]

Are you sure that the monitor back light circuitry is not failing?

I would try a different monitor and or try that monitor on a different computer.

I have tried the monitor in my laptop with VGA and works fine. 

[DeBaas]

I found this strange behaviour a few years ago in 15" Philips and LG flatscreen monitors.
As workaround I set the frequention for the monitors on 60Hz or 72Hz instead of the automaticly chosen 75Hz. When during startup the frequency is chosen the monitors came magically alive.
No bootupscreens, but a working system........
Try and play around wih the monitor settings.
For a clean restart use the handtwisting Ctrl-Alt-Printscreen/Sysrequest, and while you hold this combination press R(aising) S(kinny) E(lephants) I(s) U(tterly) B(oring). A few secconds between each pressing. Between the () is only for remembering.
Also called the REISUB combination.

[agmg]

I found this strange behaviour a few years ago in 15" Philips and LG flatscreen monitors.
As workaround I set the frequention for the monitors on 60Hz or 72Hz instead of the automaticly chosen 75Hz. When during startup the frequency is chosen the monitors came magically alive.
No bootupscreens, but a working system........
Try and play around wih the monitor settings.
For a clean restart use the handtwisting Ctrl-Alt-Printscreen/Sysrequest, and while you hold this combination press R(aising) S(kinny) E(lephants) I(s) U(tterly) B(oring). A few secconds between each pressing. Between the () is only for remembering.
Also called the REISUB combination.

Thanks for the tip DeBaas. The problem here seems that when this happens, it seems that the computer is not booting so REISUB is not working. I can only restart it or shut it down with the power button. I will buy a new PSU next week and see how it goes. If this doesn't fix things I will look for a new mainboard... (maybe write a letter to Santa? )

[Just17]

Check the BIOS settings .......  and see if setting the BIOS to do a full POST rather than a quick POST would have any effect.

The terminology changes from BIOS to BIOS but I hope you understand what I mean.

Worth a shot .....

[bicol_willem]

The first thing that comes to mind here is .... check memory (memtest)

[kjpetrie]

Do the fans run on first switch on? Is there a reset button or just a power button?

The MB battery is a distinct possibility in my mind but we need more info. On second boot you should be able to get into the BIOS. Is the time there correct? If not it is the battery.

[µT6]

as most modern mainbards the battery low status should be easy to find, or the bios warns you or you see that the system clock says the date when the bios was released many years ago 

maybe clean the ram slots and verify psu connections but more and more sounds like a mainboard problem, hopefully the new psu fix the problem