Benq G2420HD Monitor showing green lines, flickering and dots connected hdmi to lapto

[bennyboy32]

Hi

So I decided to check my new HDMI cable with my monitor before assembling my PC again.

I initially plugged in the cable and attached it to the monitor, but it gave a 'no cable connected' message, so I pulled out an old VGA adaptor and using that, opened the monitor menu and enabled HDMI auto switch, then removed the VGA cable.

Then I used windows update to install the detected driver. All was good until the install completed; I decided to turn off the monitor and turn it back on, and now everytime I do this, or change resolution, it gives some variance on the attached picture, which either goes away on its own in a few seconds or is removed using a change of resolution again or by switching the monitor on or off.

I've reverted to VGA and there is no issue, either when changing resolution or switching the monitor on or off.

Could someone please help me resolve this issue?

Do I have a bad HDMI cable/HDMI connector in the monitor or laptop? Is it a power issue?

Thanks

Pic: http://www.flickr.com/photos/8120571...in/photostream

[Domestic_Ginger]

If you can, try the following?

Second computer with same HDMI cable.
Different HDMI cable.

Should eliminate bad cable or port on your PC. If both are bad then it may be your monitor.

[Demonwar]

Usually that kind of thing is caused by a failing video card.
Check and see what graphics card each cable thinks it's using depending on the laptop spec output might be using the dedicated card and the other the on-cpu graphics.

[bennyboy32]

If you can, try the following?

Second computer with same HDMI cable.
Different HDMI cable.

Should eliminate bad cable or port on your PC. If both are bad then it may be your monitor.

Thanks for the reply, I'll try those suggestions later.

@Demonwar:

So my laptop is an x56VR 3/4 year old ASUS model, with 3470 HD Radeon Graphics, so its entirely possible it's dying but I don't really see any graphical issues when gaming (admittedly on low settings).

[bennyboy32]

UPDATE: Bad HDMI cable, thanks all