Problem with new VGA cable

[Reaper652]

I decided to move my computer underneath my desk, so I needed a longer VGA cable. I got myself a 3m one but the problem is my monitor no longer goes onto standby when I turn my computer off, it just displays a box saying "no cable connected".

It also has a problem running L4D2, it says that the resolution is not supported even though it is set at my monitors default resolution (1366x768).

Any ideas on why this happens?

p.s. happens with both a 9800gt and a 5850 in the same system.

 

[Admiral Huddy]

What happens if you put the old cable back?

Is this a d-sub or DVI? Regardless of which, both support the resolution anyway. My guess if the old cable works, there's a either a fault in the cable or incorrect pin orientation. Weird though.

 

[Reaper652]

D-sub. So this isn't a common problem with longer cables? Might have to try and dig out the receipt, or just wait until I buy a new monitor in a month or 2.

Havn't tried with the old cable as it would require moving everything (case, monitor, speakers, re-routing power...)