Monitor signal goes off randomly

By nilaykaps ·
My PC config is as below..

AMD athlon 2400+
asus MB A7V266-MX
onboard graphics card.
win xp sp3

I am not sure if this topic is discussed here but i wud like to let u know what is my specific issue.

Till recently (last 6 months or so) my PC was working perfectly fine. then it s started giving blue screen with error messgaes. I found that the RAM is faulty and replaced it.

After a month or so later.. while working, i plugged in my USB drive and suddenly monitor displayed "no signal". Surprisingly the Cabinet power LED was on, and i cud also see HD LED flickering.

I suspected some software problem so formatted the HD and installed everything again. Still same problem.

Sometimes the PC works just fine with no problems for hours..

when the PC restarts, within a few minutes the display goes off.. but rest everything working even without the pen drive connected.

Now when I connect any USB device the display goes off immediately..

I suspcted USB port problem. but I have 4 ports and it is the same on every port.

Also now it just goes off. with out even connecting anyting!

I checked the cable between monitor and Cabinet and it is fine. My monitor on other CPU's is also working fine.

This points to either PSU or the MoBo.

What could be the issue? Shall I try MoBo or PSU change?


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All Answers

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I would vote psu

by drivers1492 In reply to Monitor signal goes off r ...

I def would try a different psu first. If the usb ports are front side connected by wires to the mobo remove them from the equation by shutting down and unplugging them.

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Well as you didn't tell us about the PSU in this

by OH Smeg Moderator In reply to Monitor signal goes off r ...

It would be my first option, however if it's one of the cheap nasty ones it's quite possible that it's been passing on any Power Spikes from the mains since new and it has Degraded the components on the M'Board and damaged that beyond usefulness now.

The giveaway here the the RAM Failing. All too often people overlook the quality of the Power Supply thinking that a Power Supply is a Power Supply and there is no difference between the different ones on the market.

Unless you get a good power supply to begin with from one of the better makers like Antec you can shorten the life of the M'Board and other internal components considerably. The better Power Supplies are considerably heaver than the cheap ones and filter the Mains much better. The idea is that they will Scarface themselves and maintain the integrity of the Electronics inside the case when they get hit by something nasty.

Granted none will stop a lightning Strike but the normal Power Spikes and so on that occur can be stopped and the better ones do this.


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Another thing that I have seen as well

by OH Smeg Moderator In reply to Well as you didn't tell u ...

Is that the Monitor is suffering a Heat Related Problem and switching into Standby Mode or just not producing any display. If you can turn off the monitor leave it off for a few seconds and then when you turn it on you get a display for a short period of time before going out again it's the monitor at fault here and it needs replacing.


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Monitor is not an issue

by nilaykaps In reply to Another thing that I have ...

Monitor works fine on another PC. No issues there. Yesterday I attached a USB based mouse and it didn't work. I suspect MoBo problem. PSU works just fine.

I am not sure but it can be that the cable between CPU and monitor "might be faulty". Will replace that and check today.

Thanks for your suggestions and waiting for more... :)

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Why do you think that the PS is working properly?

by OH Smeg Moderator In reply to Monitor is not an issue

Even if you measured the actual Voltages that it produces and there are 3 or them you have no way of actually measuring the Current available on each different Voltage Rail.

I can remember one customer who bought a new HDD, M'Board, CPU, RAM, Optical Drive, Camera and so on to fix a problem of the Monitor showing a No Signal message and all that was required was to replace the PS with a working on. Apparently it was producing the correct voltages but on the 5 V DC Rail there was no current so that when it got a load the volts dried up and that part of the M'Board, & Video Card where not working.

With the current generation of Power Supplies the only reasonable way to check them to to fit a Known Good one and see if there is any difference. Then if there isn't fit that PS to a different computer and see if that works. If it doesn't the PS was damaged when you applied power to the Problem system.

Just because Fans spin doesn't mean that the PS is OK just that there is a minimum of 8 V DC on the 12 V DC Rail and that there is enough current to start the fans spinning. It in no way implies that the 1.3 V or the 5 V DC Rails have any power or current.


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I will check the PS now.

by nilaykaps In reply to Why do you think that the ...

I changed the cable between CPU and monitor and no improvement. So cable fault is ruled out.

I have a USB based device, which draws power from USB port. As soon as I connect it the display goes off, with CPU power still on.

As of now even if i plug my pen drive in ANY of the 4 USB ports the display is fine.

Yesterday i was copying around 10 GB data from C drive to D drive. There was no USB device connected at that moment. after a couple of minutes into the data transfer, the display showed no signal. same problem, but with NO other additonal USB connections.

To isolte USB port issue, I got a 4 port USB PCI card to test it. I installed the card and my pen drive worked just fine. But ANY other uSB device when plugged, display goes off, no signal.

I think either the MoBo is faulty or the PS. And I want to believe OH Smeg. I will test the PS on a different machine and test it again..

Will udate you in a couple of days.

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Found the problem

by nilaykaps In reply to Monitor signal goes off r ...

Well, it is weired but I did clean up of my registry and deleted unwanted files and just cleared the junk from from my PC.

Then I installed a PCI USB card and used it instead if my on board USB port. Everything worked perfectly fine! no monitor going off, no random reboots and nothing.

I suspect my on board USB hardware is faulty and have already found the alternative.

Thank you all for your suggestions and time to post your replies..

cya soon :-)

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