How to Benchmark Your PC

Whenever you read a PC review or a component review, benchmark results typically accompany it. Such results are most often in the form of numbers, such as a score or a frames-per-second total. Sometimes they're relative, in that the result is posted as a multiple of some reference system or number.

Because benchmark scores mostly appear in product reviews, that's how people frequently view them--simply as a way of comparing products. But benchmarking is useful for more than just figuring out what graphics card to buy.

• Benchmark software can help to stress-test new systems (particularly important for PCs you assemble yourself).
• Benchmarks can test for sudden performance issues. If your system has apparently slowed down in some way, you can use before-and-after benchmarks to confirm your suspicions.
• You can run some benchmarks to check whether certain tweaks you've implemented on a system actually speed things up or not.

There's more to benchmarking than simply installing the benchmark software, firing it up, and running it at whatever default settings exist. I'll walk through the reasons you may want to benchmark in more detail, and then I'll discuss how to properly run a benchmark.

Before diving into the whys and wherefores of benchmarking, let's start with my Golden Rule.

Loyd's Golden Rule of Benchmarking

It's a simple rule, and it applies to most users who aren't professional product reviewers: Run benchmarks that give you information about what you want to do with your PC. Anything else is irrelevant.

If you're primarily a PC game player, you probably care about how well games run on your system. Secondarily, you might care about 3DMark scores. In contrast, a Cinebench score or a Photoshop-filter performance test won't be as important to you.

Of course, most people use PCs for more than one purpose. Even so, you probably use your PC for one purpose more than you do for others, so it's worthwhile to focus on how well your system performs in that arena.

By the way, there is a corollary to Loyd's Rule: If your PC runs games very well, it will run just about anything well.

You'll find some narrow exceptions to that rule. For example, if you want to use an architectural CAD application, a system that runs games smoothly will likely do fairly well with that CAD app--but it would probably perform even better with a professional graphics card. At the same time, if you use a pro graphics card, game performance will likely decrease a bit.

Also, it's true that a great gaming system will run office applications very well, but if you're using office apps exclusively, you probably don't need a high-performance graphics card--and certainly not two of them.

Finally, keep in mind a general exception to Loyd's Golden Rule of Benchmarking: If you're a PC-performance geek, you'll be driven to dissect the performance of every aspect of your PC.

Most people don't care if the primary hard drive is a little slower than a newer model. PC-performance geeks are obsessed with knowing just how much slower their current drives are in comparison with new models. It's just the way their brains work--I should know.

Stress-Testing Your System

When you build a system, you naturally want to test it, to make sure everything works well. You can use software designed to test a system, but those programs don't always do a good job of verifying system performance. In the past I've run 3DMark 2006, which allowed you to loop the test ad infinitum. To heat things up a bit, I'd also run the multicore version of Mersenne Prime95 simultaneously, using the benchmark mode of Prime95 that consumes lots of memory bandwidth.

Whenever I burned in a system this way, I ran both applications simultaneously for 2 to 4 hours.

It's my belief that system burn-in isn't as necessary today as it once was. One of the reasons to burn in a system was to check for early component failure: If all the components survived the burn-in process, they'd likely run for years without issues. Today, components are generally more reliable. If you've built your own system, though, you'll probably want to run a few stress tests to confirm that it's stable at a high performance level before you get started with any serious gaming or other taxing tasks.

Benchmarks for Troubleshooting

If your system starts to feel sluggish, try running a few performance tests. Whether the game frame rates seem to be slower than before, or the hard-drive performance appears to be declining, or you just get the feeling that the PC has become less responsive, running performance tests can possibly help you spot significant problems.

Once, my PC's game performance suddenly slowed to a crawl. It turned out that my system's cooling fans, including the GPU and CPU coolers, had become clogged with dust. That resulted in high enough heat levels that both components throttled back significantly.

If you want to use benchmarks as problem-solving tools, first you need to run some tests while your system is healthy, so that you have a baseline for comparison.

System Tweaking

If you overclock your system, or if you just like to play around with different graphics settings, running benchmarks can give you some idea of the impact of a tweak. If you really want to verify the positive or negative effect of a setting change, though, you need to be patient, and change only one setting at a time before rerunning a test.

Remember the Golden Rule of Benchmarking--use tests that are applicable to what you want to do with your system. For example, you may find that altering some memory timings could have a huge impact in a synthetic memory benchmark, but video-rendering time remains the same.

Now that you've looked at the whys of benchmarking, it's time to dive into how to run a benchmark effectively.