Hello, basically my parents were using the computer as normal when the screen went a darker colour with horizontal lines, so they held the power button until it went off but within a second it comes back on with a very loud whiring noise, louder than normal, and the screen says no signal, any ideas?

Oh the computer is a desktop compaq presario

Double check that the cable going from the monitor to the tower is snugly fit in place. If it is, try the monitor on another computer (if available).

It is difficult to say for certain what is wrong without seeing the computer. But what you described leads me to believe that either the monitor is bad or the video card is bad.

Which model Presario is it? Have you made any upgrades to it since it was purchased? Chances are if it is not the monitor, you will be better off purchasing a new tower. Especially if it is as old as I think it might be.

Hello thanks for the reply, not site what you mean by the tower (not great with computers)
It's a compaq presario SR1000

Have tried the monitor and that works

Have also opened and cleaned all the fans, also left the computer near the window to cool to see of that's why the fans were working so hard but no luck.

That I know no replacements have been made and the only change is that I have two hard drives

When a monitor goes black there are a few culprits and a few things to do to narrow down the issue.

As stated above you first want to check the easiest things first. Below is a list of things I would check:

1. Video cable is snug on both ends.
2. Test monitor by using another PC. With same video cord. (if applicable)
3. Test PC by using another monitor. (if applicable)

If #2 varifies that the monitor works and you used the original video cord then you can narrow the issue down to the PC itself.

It could be a video card malfunction. In my experience with this issue a majority of the time its either a bad monitor or a bad video card. Ive never seen a bad VGA Cable!

Okayy I'll check it now, many thanks!(: