ESD also known as electrostatic discharge can wreak havoc on computer components when servicing a computer. Grounding yourself is what is commonly known amongst computer repair technicians, builders, etc to diffuse ESD electrostatic discharge. One quick way to properly discharge yourself when working with computer components is to just simply touch the computer case on the chassis and or power supply every so often.
You want to make sure that this computer is not plugged into live power. Even if you turn off the computer and turn the power supply switch to off position, this can be dangerous because you are in effect earth ground. You want to make sure that the power cable is not plugged in.
You might also want to press the power button for thirty seconds to one minute to diffuse any ESD electrostatic discharge remaining. Then you just touch either the power supply itself or chassis. If you work on electronics and personal computers quite often, you could purchase an anti-static mat.
They are made out of rubber and will clear ESD electrostatic discharge. These mats come with snap in connections, so that you can connect yourself to them via an anti-static wrist strap. You can also just connect the metal clip on your anti-static wrist strap to these mats.
Another option are to purchase anti-static gloves. They too have a snap in connector to hook to an anti-static mat. Also, you could just connect this anti-static glove to the computer case or power supply just like an anti-static wrist strap.
Holding your components properly can also help. If you have a multimeter you could measure in ohms how much charge you, your computer, and your components have. Then you can measure the difference by using one of the afore mentioned ways to clear ESD electrostatic discharge, and then using your multimeter to measure ohms.