Half-life 2 and Portal 2 graphics are corrupted

Question

I recently bought a new 1080p monitor to replace my ageing 1280x1024 one. The new one uses HDMI and is connected to my PC via DVI. The old one used a VGA cable.

Set up was fine (Windows even detected the new resolution) however when I run Half-life 2, the graphics appear to be corrupted. Many of the models are missing triangles which means that you can look right through them. Also quite frequently you get a blurring effect which causes a streak of colour to run across the screen.

I also ran Portal 2 and it suffers from the same problem. Both games ran just fine on the old monitor at a much lower resolution.

A couple of examples are below:

Even more screens (at a higher resolution) can be found at http://imgur.com/a/kgQsZ.

Is this a case of the graphics card (Radeon HD 3650, running at 720p - as it's too jerky at any higher resolution) just not being up to the job? The textiles inexplicably corrupting but only at high resolutions? Or something else?

Can anyone advise me on how I can fix this?

EDIT: I forgot to add that I'm running all the latest updates from Windows Update as well as the latest graphics card driver. I've even tried re-installing the graphics card drivers but that didn't change anything.

Answer 1

This is usually a sign of a dying graphics card. Try running other games that aren't run on the Source engine and see if it still happens, if it does, it's likely your graphics card at fault.

Also try reinstalling your graphics drivers or updating them if possible, and check what temperature your GPU is running at (I know you haven't changed anything but your monitor, but it can't hurt to check).