Overclocking a computer—tweaking its internal clock speed to boost performance—has been a tradition of modders and hackers since the early days of PC clones in the 80s. Overclocking Macs hasn't had quite the same level of popularity, in part because Apple tended to make it difficult to do. But some brave folks have taken to overclocking their Macs; I moved around some tiny surface-mount resistors on my iMac to overclock it 33MHz, back when that was a significant improvement. But these days, it's possible to tweak CPU and bus speeds via software tools. The folks at ZDNet.de have put together an overclocking tool for anyone to use, not just those with "hardcore knowledge."

Now, before you salivate at the chance to get a "free" performance boost, remember you rarely get somethin' for nothin'. Overclocking works because most chips used in computers are rated at a speed at which they are guaranteed to work; many can work at higher speeds, though slight differences in manufacturing means there is no way to know 100 percent without trying it first. ZDNet.de tested the tool with a few Mac Pros and found performance gains of up to 20 percent. But pushing the pedal to the metal on your computer can result in instability.

In particular, tests show that no-name or cheaper memory upgrades tend to not work as well as pricier, name-brand memory when overclocked. That is because cheaper memory uses chips that typically operate just fast enough to pass testing, without having much overhead. Trying to push it beyond its rating will make it fail, and when your RAM fails, so will your computer.

Another major caveat is that due to the way Macs keep track of time, the clock on your computer will start to speed up. Some Mac Pros can overcome this by rebooting after overclocking via the software tool, but some cannot. If your boss is easily fooled, however, you may be able to take advantage of the time speed-up by getting to leave work early.

If you have a 2.8GHz or higher Mac Pro or Xserve, though, even a relatively modest 10 percent performance boost might be worth the time to try the tool and check for stability. Because the tool works via software, and not hardware, the changes can be reset after a reboot. So, it's relatively safe compared to changing jumpers or soldering resistors on your logic board. Even if you're not the type to throw caution to the wind, with this tool, you can now give overclocking a shot. If you're not keen on hauling the company Xserve to the Genius Bar after you tweak it beyond recommended limits, however, you may want to just stick with the factory settings.