How To Troubleshoot Your Home-Built PC

Building a PC is a little like walking a tightrope without a net. Okay, it's not quite that dangerous, but unlike buying an off-the-shelf system, you have to be your own tech support staff. Sure, you can try to get support from individual component suppliers, but that can be frustrating--your motherboard maker points at your memory suppliers, who blames your graphics card manufacturer, and so on. Before you know it, the money you saved from building your PC has been outweighed by the time you spent getting it to work.
Fortunately, we have a few tips that can help you find and fix your home-built PC's problems. First, we're going to cover some troubleshooting tips, and then we'll take a look at some common issues with DIY PCs.
How To Troubleshoot Your PC
Here are a few tips to avoid getting stuck in a troubleshooting rut.
State the problem clearly, even if it's only to yourself. If you need to, write it down. "The system won't boot" isn't good enough. Instead: "The system won't boot; when it tries to boot, it generates an error saying that no operating system is installed. When I try to reboot, I can see that my hard drive isn't visible to the BIOS."

Pay attention to your system's changes. If something isn't working that was working before, ask yourself, what's different? Was an app installed? A new driver update? A BIOS update? In the above example, of the system not booting, you might realize that you just installed a second hard drive in your system.
Make only one change at a time. If you're experienced, it's particularly tempting to shortcut this process. "I'll update the BIOS, detach the second new hard drive, and swap out the power supply." If the system starts working, you don't know what actually solved the issue. If the system still doesn't work, it's possible that one of your multiple changes may be the new cause of the problem. Make one change at a time!
Document your changes. You don't have to keep a detailed lab notebook. Just grab a sheet of paper and note each step along the way, what worked and what didn't. Once you solve the problem, throw the page or pages into a folder for future reference.
Getting frustrated? Walk away from the problem. A little downtime can bring new inspiration or help you catch clues you may not have noticed.
Ask for help. If you're still having problems, bring in a second pair of eyes. Even a nontechnical person can make useful suggestions, if you've explained the issue clearly. Also, try an online forum (like the PCWorld Forums). If you go online for help, make sure you present a detailed description of the problem, including brand names and model numbers, if appropriate.
Using a well-defined process to work through problems will result in speedier, more satisfying solutions--and save you a few bucks. While it can be tempting just to throw money at a problem ("This motherboard is dead! I'm going to go buy a new one!"), make sure to pull out your credit card only after you're sure you'll need it.
The System Won't POST!
Every PC goes through POST--power-on self test--when it first powers up. One mistake many new system builders make is to assemble the entire system, then try the first boot. The problem with this approach is that it's difficult to narrow down the actual culprit behind a boot problem. Instead, install the CPU (with CPU cooling solution), memory, and (if applicable) the graphics card. Don't connect hard drives, external storage, or optical drives. Don't install additional expansion cards yet, either. Try a bare-bones boot first, with only the monitor and keyboard attached to the system.
With that in mind, let's look at first-boot issues.
Nothing happens on startup. After attaching the monitor and keyboard, you press the power switch and... nothing. The fans don't spin up, lights don't come on. The system appears to be completely DOA. While it's possible that the motherboard is completely dead, it's been my experience that defective motherboards will still light up their diagnostic LEDs. If you're getting no indication of power, something else is likely the culprit.
Is it plugged in? This may seem like a ridiculous thought, but it's worth checking the power. Even if the power cord is plugged in, I've found that the plug to the system PSU might not be firmly seated. I've also plugged systems into power strips, but the strip itself wasn't turned on or plugged in.
Check the switch on the power supply to make sure it's in the "on" position.
Check the internal power connections. Ensure that the main power and the ATX12V connector (a small 4- or 8-pin connector) are both firmly attached.
Check the power switch and reset switch connectors. I've sometimes reversed these, and discovered I've made the reset button the actual power button by accident.
Check under the motherboard--you might have a grounding problem. I once found a motherboard mounting nut installed in the wrong location inside the case. It was in exactly the right place to create a ground fault in contact with the back of the board. After removing the nut, the system booted without a hitch.
If possible, try another power supply. A dead power supply can certainly prevent a system from powering up.
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