Reassembling the Computer

Same Way, Only Backwards
When it comes time to put a computer back together, it's usually just a matter of reversing the order in which you took it apart. Again, you're going to visualize each step because there may be an easier way. Is it easier to install the motherboard or the power supply first? Are the RAM DIMMs (or SIMMs) easier to access before, or after the power supply is in. If the motherboard pops out the back on a tray, then install the CPU and the RAM before replacing the tray. If you install the power supply first, then you may be able to clip the power connectors on as you install the motherboard and tray.

Tools
When putting the computer back together (or disassembling it for that matter), there are some basic tools that you'll find handy. Of course, you'll need your ESD protection equipment and a phillips screwdriver (keep a flat-head screwdriver nearby, too. A small flashlight and a magnifying glass may come in handy, as well as needle nose pliers. A useful device for any kind of computer work is a small srewdriver with a phillips head on one end and a flat-head on the other (I have no idea what the proper name is for the tool). Once again, you're not in a race. A good carpenter measures twice, and cuts once. When working on computers you want to double-check everything you install or connect. Before you start, make sure you have taken all your ESD precautions. As you continue, make a conscious effort to remain aware of these precautions.

The Power Supply
A fairly basic installation, just lineup the holes and screw it on. Don't plug it in yet. Remember, the cable going to the remote switch on the front of the case carries 110 volts AC. If you took the wires off the switch, make sure you connect them just as they were before (I hope you documented). A wrong connection here can burn up your PC. After your power supply is installed, do not plug it in, you may not be able to tell if the switch is on or off and you don't want to turn the power supply on without a load.

The RAM
DIP memory modules are the hardest to install. Luckily, it's not done much anymore. SIMMs are inserted at about a 45 degree angle then stoand up until they clip into place. If they don't clip in properly, maybe you have them in backwards. They'll usually have a key cut into one side. DIMMs are keyed on the edge connector side, they can only be inserted one way. Once they are lined up, push them down until the locking tabs on the side come up. You may have to support the motherboard from underneath if it looks as though its going to flex too much. COAST modules are also keyed on the bottom and insert much like an adapter card (Coast On A STick memory is cache SRAM).

The CPU
Luckily, CPU sockets aren't friction fit anymore. If you have a PGA Central Processor (Pentium MMX or Celeron, Cyrix or AMD), it will fit into a ZIFF (zero insertion force) socket. Pin#1 on the chip has to be lined up with pin#1 on the socket. This can be indicated on the socket with an arrow, a #1 silk-screened on the board, or a flattened corner. Usually the CPU will indicate pin#1 with a flattened corner (and, or a dot on top, and, or an arrow on the bottom center of the chip). Unclip and lift the handle, insert the chip, lower the handle and clip it in. If it's a Pentium II or a Pentium III, it will fit into a Slot 1 socket. These are rectangular in shape and have 242 pins in two rows. They're keyed, and the cartridge should only fit in one way. Check any documentation that came with the motherboard or CPU, and refer to your notes.

The Motherboard
Most PC cases will allow you to remove the metal tray that the motherboard attaches to by removing 2 or more screws. If you didn't do that during disassembly then you should familiarize yourself with it now. The plastic standoffs on the motherboard are to keep the solder-side of the board from touching the metal case and shorting out. Usually, it's better to install the RAM and CPU first to avoid the possibility of flexing the board and cracking solder connections or traces. Orient the motherboard properly and either clip in, or slide in the standoffs until the mounting screw holes line up. Insert the screws that hold the board in place. The screws need to be snug, but do not twist them into the motherboard. You may be able to connect the power to the system board as you install the tray. A power supply with a baby-AT form factor will have two motherboard connectors (P8 and P9). These connectors are keyed but can be reversed. Make sure the black wires on the two connectors are beside each other. Clip the keyed edge in at an angle, then straighten the connector up and slide it on. ATX power connectors slide in until the tab clicks. Once the motherboard and tray are secured in place, you can re-install the wires for the front of the case (refer to your documentation).

At this point, you can install the video card. Do a final check on everything installed. Re-check all installations and connections, attach and plug in the monitor. Turn the computer on. Watch for lights on the front panel. How far does the BIOS POST routine get? Are there any error messages? Is this expected?

One thing that I don't like to do is to completely re-assemble a computer and then just turn it on. If it doesn't work at that point, then you have to tear it all apart again to find the problem. Once you've installed the power supply, motherboard, CPU and RAM, install the video card, hook up the keyboard and cables and start your computer. Of course, there's no drives installed and some expansion cards are missing, so you're going to get errors. But if it recognizes your video card, counts the memory and allows access to you CMOS setup program, then you know everything installed to that point is working. Now, turn your computer on after installing each new device. If you get an unexpected error, then it should be due to the last device you installed.