Random Access   chris, kp & rob
In The Lab
Build Your Own PC Chapter 4: An Ounce of Prevention
by chris & rob
Chris: With the DDR memory and CPU upgrade kits, we are just about ready to start putting things together in the chassis. Before we take the parts out of their boxes and start dropping them in place we need to take a couple of precautions.

Rob: All of our readers know about precautions to take when you open up your case and mess with the guts but let's go over it again for posterity. What's the first step?

Chris: First we want to take some basic ESD (Electro-Static Discharge) precautions. Ideally, we want to set up on a clean table or bench away from carpet or upholstered furniture. Don't handle the memory, CPU or cards until you are ready to install them in the system. The typical anti-static bag can protect the component against small discharges of maybe 500 to 600 volts. While you won't even feel this level of discharge, that 5-volt circuitry of whatever component you may be touching certainly will. Circuits can be damaged by static voltages as low as 400 volts. Static is all around us, especially in the winter when humidity is low and static build-up is worse then ever. Did you ever get zapped by touching something metal like reaching for a doorknob?

Rob: I get shocked all the time in the office. Why, just this morning I walked across the carpet and touched a file cabinet. It gave me quite a jolt. Chris: If you could hear the snap from the spark, you just discharged more than 5000 volts - more than enough to kill that brand new video card, memory, or CPU.

Rob: 5000 volts sounds like a lot. Good thing I wasn't holding any components... even in an anti-static bag.

Chris: If you don't kill it outright, damage from ESD can reduce the life of the component or cause intermittent problems early on. ESD failure is NOT going to be covered under warranty!

Rob: Well, let's do whatever we can to make sure our parts get into the case without getting zapped. How do we ground ourselves?

Chris: The easiest way to dissipate static electricity is to use an anti-static wrist strap, which connects you to AC ground. This will equalize the electrical potential between you and any component you may touch. I have a basic conductive wrist strap that has an alligator clip on the end to clip to the chassis, but to be fully effective, the chassis must be grounded and it can't do that if it is unplugged. If you don't have a wrist strap, the next best thing is to touch the grounded chassis before handling of any electrical parts. It's a juggling act but it's better than nothing.

Rob: No worries here, we're professionals and we've ponyied up the dough for wrist straps (typically from $6 to $10). Now that we're grounded to the chassis, what about grounding the chassis?

Chris: Examine the power supply in the system chassis. If it has a power switch we can connect the power cable but leave the switch in the off position; this connects the electrical ground but disconnects power. If there is not a power switch on the power supply, connecting to a surge protector with the power turned off will fulfill the same purpose. We don't want power on when we start making the connections to the system board or installing the CPU or memory. Most system boards have a power LED on the board that is illuminated as a warning any time the power supply is connected (and on, if there is a switch).

Next month we start putting all the pieces together... really.

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