Why are odd patterns appearing on my monitors shortly after startup?

Q  I am experiencing an unusual display problem, which occurs around 10 minutes after powering up my PC. I have connected a different (spare) monitor and cable but the same fault occurs, though with a slightly different pattern.

I assume this experiment shows that monitors are not at fault? However, I have also checked that all cables are tight and the internal components, including the graphics card, seem secure.

I have used the Microsoft Safety Scanner anti-virus tool suggested in issue 364 and it has reported no problems. Do you have any idea what might be causing this?
William Rogers

A  When we first read your letter we suspected either a driver problem or hardware fault. However, on a second read we realised that we had inadvertently overlooked the time aspect – and that leads us to suspect even more strongly that this is a hardware fault.

Specifically, it could be that the graphics card’s cooling equipment is failing in some way. Typically, this means that a fan stuck onto the graphics card may have become stuck or so caked with dust and grime that it has become ineffective. As a result, the processor (or other components on the card) may be becoming too hot, leading to the curious effect you are seeing on screen.

So, we would suggest in the first instance giving things a good clean to see if that helps.

Alternatively, there is still the possibility of a problem with the drivers. It could be, for example, that some other program is clashing with the graphics drivers somehow, but the issue reveals itself only after some unknown (to us) trigger.

One way to check this theory would be to start Windows in Safe Mode (press F8 shortly after powering the PC and then select Safe Mode from the menu): if the graphics problem doesn’t persist in Safe Mode then it points to a driver problem, so download and install the latest set from the manufacturer’s website.

However, if the visual weirdness continues, then it is almost certainly a hardware fault. As there’s unlikely to be any realistic prospect of a repair, a replacement card will probably be in order.