No signal between PC and Monitor. what is problem?

New Samsung Monitor, exchanged 2x because I initially thought problem is monitor .
Problem is PC, a several year old Dell Optiplex GX270
Suddenly the desktop cannot communicate with the monitor.

Computer boots, see the Dell splash screen, but then no further image on the monitor. I can hear the fan, keys light up on keyboard so I presume the bootup is continuing but no connectivity with monitor ( any monitor). Sometimes, after four, five tries, the boot up does succeed; Dell splashscreen, then Windows XP and on through log in and full boot up. But t within minutes , while i have started working, especially if I try to open control panel, the screen again goes dark and I get the  message that the monitor is not getting signal.

Local repair shop checked power supply, replaced video card.  Initially all seems ok in repair shop,computer boot ups but when i get computer back to our office the problem persists Told by techie that the mother board is bad..Could this be it? IF so, is it worth repairing? Is there some other component which may be causing the problem.
Anyone out there with some ideas? Has anyone had similar problem? IS it time to get a new computer?

  config_error 07:10 04 Feb 09

your monitor is not capable of your current windows desktop resolution, try to boot in safe mode

when the computer starts press F8 you will see the boot menu. use arrow keys and select boot from Safemode once in the windows safemode change your desktop to 800X600 resolution then restart your computer,. you will now see your desktop, now change to 1024x768 or higer and see if your monitor is capable of the desktop resoultion..

visit click here

Thanks but I don't think that is the problem
Monitor and CPU did work well for over 6 months.
We used resolution of 1024 x768 or even greater and all was fine.
Plus its mate, the twin computer we are using (same type) is doing well with its 19" Dell monitor also set at a higher resoultion that 800 x 600. So I am not convinced that is the reason for current failure

  MAT ALAN 19:41 04 Feb 09

Is there some other component which may be causing the problem.

You have already eliminated the monitor and the VGA card as not beingthe root cause of the fault, apart from maybe a bent pin in the cable plug you only have the MOBO left...

IS it time to get a new computer?

you have a several year old computer as you say, the answer is probably yes then asuming that if you where to repair the one you have is going to stand the test of time...

  jimv7 19:44 04 Feb 09

Does the dell have an onboard graphic card as well as a stand alone one, and are you plugging the monitor into the wrong 1.

The repair shop techie told me that the motherboard is ' not good" but I don't know how he knows this.
I trusted the shop until the techie mentioned, when telling me the MOBO is "not good" that I can purchase a reconditioned CPU from them;they will take back the new video card and apply it as credit to reconditioned CPU.Cost of CPU = couple hundred dollars. I became more skeptical when he told me that if I purchase such a computer I could not swap out my HD (which is running well) with the one in the CPU.. " You cannot put in another drive". That makes no sense to me.I have swapped out drives in computers for years,both PC and Mac.
Hence my gratitude to you folk as I suddenly wonder how much i can trust the repair shop. (Has been inexistence over 12 years but that may not mean much)

I am not sure what the difference is between an on board graphic card or a stand alone. There may well be an "on board" graphic card as well as the one inserted in the card slot that I can see.The cpu does show two monitor ports. From the day I purchased from Dell and had Dell help setting up, I used the current port. OEM had a port with two VGA plugs so that the CPU could handle dual monitors. We never used this feature. The new video card inserted has only one port.Familiar royal blue VGA. The other small female port , on the side is one I never used and do not know what it supports.

We have only used the one port since day one.
I also, would doubt a bent pin since a) I checked the plug b) the problem started after more than six months of working beautifully with hte Samsung 932BWPlus monitor attached. The problem started while everything was hooked up, out of the blue.

  Devil Fish 20:49 04 Feb 09

have a look in device manager for the driver if it is listed as generic ie plug and play monitor it may be worth heading to the manufacturerswebsite to see if you can get the inf file for that monitor and install that see what you get

If I can boot up with a monitor, I can look up the device manager. Right now, cannot see anything.
No monitor works with the computer, including a Dell monitor which is working perfectly on our second Dell Optiple GS 270.
And the Samsung had worked fine with the "sick " computer": for over six months.

thank you for your advice.

This thread is now locked and can not be replied to.

Nintendo Switch review: Hands-on with the intuitive modular console and its disappointing games…

1995-2015: How technology has changed the world in 20 years

This abstract video touches on division in our technologic world

Best alternatives to iTunes for Mac | Best music players for macOS: Free your music from the…