Mac mini video randomly flickers
Q I have a late 2012 Mac mini. The computer is on 24/7, with a screensaver after 10 minutes, and screen power shuts off after 15 minutes. Lately I’ve noticed that there was a ‘tearing’ effect across the screen. I swapped out the HDMI cable for a VGA dongle, and it seemed to clear it up. However, I’ve again noticed this tearing effect, although now much smaller, in random places on the screen. It will typically be about 5mm high, and up to 10 or 20mm long. It may appear as a line of shapes across the display. It flickers almost like electrical interference – but I can’t locate any device that may be causing it. The effect is not there all the time, and I am unable to make it happen. I’m wondering if my video is failing? How can I check it? Would it mean a mum board replacement? Robert Chalmers A This sort of graphical glitch is a classic symptom of an overheating graphics card. But the Mac mini uses Intel HD Graphics 4000, which is integrated on the same silicon as the CPU, so you can’t simply replace it. A complete replacement of the ‘mum board’ (in 25 years, this is the first time I have ever heard the motherboard called this – I love it!) might fix the problem for a while, if your mini is overheating because of dust build-up. But that’s unlikely after just a year or so. And it’s a sledgehammer to crack a nut in any case.
Graphical tearing is an early warning symptom of overheating. It kicks in well before the graphics chip gets hot enough to cause permanent damage. If the mini’s fan is still spinning, make sure the airflow isn’t obstructed and you don’t have stuff stacked on the top. If the fan isn’t spinning, well then there’s your problem and you should get that replaced immediately.