When you remove a PCI/PCI-E/AGP card from your machine you might not bother putting a cover over the gaping whole you now have in your machine. Why would you? It’s not like you’re going to be throwing things into it? Here’s why you should.
If you don’t you might unplug your headphones from the back of the computer and, instead of stowing the cable away somewhere safe, you might just drop it in order to connect the speaker cable.
Now, if you’re unlucky – like me – that headphone cable might fall through the gap in the back of the computer, on to your graphics card where it might connect two piece of metal which were not designed to be connected in such a way. If this happens your computer may well shut itself down, making your heart descend like the sound of the fans.
Now, if you’re lucky – as I was – you can remove the cable, press the power button and everything will work perfectly. However if you’re unlucky….well….bad luck.