Monitor nonpreset mode and blackout problem

[Ornamexito]

Hello, i got a 17" Benq Q7C3 at a car boot sale. I plugged in the power cable and the VGA cable, the monitor works fine but i only see the image from the computer for about 2 seconds, then it said "nonpreset mode !" and it turned black.

I read some posts and i found out that i have to change my resolution to 1280 x 1024 , so i did. Now when i turn my monitor on, again i see the image for 2 seconds BUT this time the screen turns black without it displaying "nonpreset mode !".

Please help what do i do?

 

[Ornamexito]

Dont worry anyone, i plugged in a 19'' TV to my pc and it worked