This is by way of general advice regarding static electricity and why we should reduce the risk of the damage it can cause.
As may be known and understood, a large part of the operation of a computer is all down to the humble transistor. We may talk of chips, and CPU's, including all the other components and add on graphics cards, sound cards or other general upgrade cards, however they all contain transistors, in the case of a CPU thousand upon thousand of them.
The modern transistor as used in chips and CPU's, are based on what is known as the MOSFET technology.
Without getting too technical, this type of transistor, in order for it work, relies on a microns thin insulating layer, which does exactly that when working at the devices designed voltage. Which for a CPU is fairly low, other devices a little higher, hence why power supplies have different output voltages, however the highest used in the modern home PC is only 12 volts.
Manufacturers do provide some minimal form of over voltage protection to their devices, unfortunately it isn't bullet proof.
Just about everyone has at least witnessed some form of static electrical discharge, from hair standing on end, to blue sparks jumping across a quarter inch or six millimetre gap. Those voltages are incredibly high, and can be up to ten or twenty thousand volts for it to jump that gap.
However, lower static voltages are present all of the time, which in most cases dissipates harmlessly into the surroundings.
You yourself can have quite a high static voltage present between yourself and any other object at any given time, however you don't notice it, as while either sat down, or just getting hold of the door handle to leave a room drains that voltage away.
In most cases static electricity holds very little actual power, it drains off slowly and therefore you feel no electrical shock or not even a tingle.
Static electricity occurs due to movement and friction, walking or moving across a nylon carpet is possibly one of the highest and quickest ways to create it. I personally have seen a spark jump over half an inch in an office environment, when a cable I was fitting had been dragged across the nylon carpeted floor. However that was an extreme circumstance.
So when working on a computer which as I said earlier contains transistors that depend on that microns thin insulating layer, which is what makes them so static sensitive. It makes sense to make sure there is no high static voltage present between yourself and the computer.
Without first touching the case, just in order to make sure any static charge in yourself is drained off to ground, any high static voltage hitting a sensitive component, is the equivalent of firing a large armour piercing shell through a layer of tissue paper as far as that very thin insulating layer is concerned inside each and every transistor. That obviously ruins the transistor or transistors affected.
Please do take precautions and eliminate the risk of static electricity building up by maintaining some electrical contact between yourself and the computers case or components, a hand on the case, or just touching it for most of the time, or better an anti static wrist strap.