Running an overclocked PC is not a problem, provided that the PC is stable at the overclocked settings. Several programs are available to assess system stability by stress-testing the overclocked system. However, most overclockers do not know that the Linux kernel is an exquisitely sensitive tool to detect instabilities in an overclocked system. In fact, it is more accurate and sensitive than either Prime95 or IBT/LinX. The Linux kernel supplies users with a dead simple method for measuring hardware instabilities - like those caused by an `unstable` overclock. There is nothing special to install as this functionality seems to be naively included in the kernel itself. To use it, simply run a standard stress test such as Prime95 or Linpack and watch the output from dmesg. If the system is unstable due to insufficient voltage settings, excessive heat, it will report..."
Slow computer got you down? Maybe a hardware upgrade should be in your cards, if so this guide to the Fundamentals of Upgrading a PC is an invaluable read. PCSTATS Tips