Overclock Your CPU, GPU, and RAM

You want the best performance possible from your computer, but you can't afford any hardware upgrades. No problem--we'll show you how to safely overclock your existing desktop PC's CPU, GPU, and RAM and give it an extra shot in the arm.

Safety first! Modifying components like these could void your warranty (though some PC parts are sold specifically for use by overclockers, and their warranties tend to be more lenient). Also, no one will replace equipment that has been physically damaged by overclocking, so make sure that you're completely comfortable taking your PC's life into your own hands before you change anything.

It's important to have system-monitoring software to keep track of your tweaks. CPU-Z is good for tracking your various components' speeds. In addition, clean your PC's case thoroughly and keep your components as cool as possible. Overclocking entails pushing your PC past its specified peak performance, and the extra power creates more heat, so you may want to consider adding extra air-cooling equipment. Better yet, see our instructions on how to build your own liquid-cooling system.

Overclocking Your CPU

The advertised speed of your CPU is calculated by multiplying the base clock rate by a multiplier. To get more performance from your processor, you need to increase one of these two variables. If you don't have an unlocked processor (Intel's K-Series and Extreme Edition, or AMD's Black Edition), you'll have less flexibility, as unlocked processors offer more multipliers to adjust. But you'll still be able to get some extra mileage out of your CPU.

You can tweak the multiplier in your BIOS.
We tried overclocking a test machine running one of Intel's unlocked K-Series chips, a Core i7-2600K CPU running at a base speed of 3.4GHz (that number is the product of the processor's base clock rate, 99.8MHz, times the multiplier, 34). With K-Series chips, you can easily modify the multiplier from the ‘Performance' settings in your BIOS. Just boot into the BIOS, increase the CPU multiplier number by one, save, and boot into Windows.

Check the Core Speed and Multiplier tabs.
If this boot doesn't produce error messages or furious restarting by your machine, you're on the right path. Check your system specs via CPU-Z to confirm that your settings held-they can be lost if something goes wrong during the tweaking process. On CPU-Z's ‘CPU' tab, look at the number under ‘Core Speed and Multiplier'. That number will fluctuate, depending on what your PC is doing from moment to moment.

Next, run a benchmark utility to stress-test your CPU's new configuration. Use Prime95's Torture Test mode or Linx to push your PC to its limits, thereby giving you an idea of your system's maximum clock speed. If your computer remains free of blue screens or sudden restarts after a few hours of number-crunching with one of these tools, you're probably in the clear. Then you can stick with the current overclocking settings, or try again with a slightly faster speed.

Overclocking Your GPU

Overclocking a modern graphics board is easier than ever; most of the time, you can raise performance by turning up a few sliders in your GPU configuration utility.

First, make sure that you've downloaded the latest drivers from the manufacturer's Website. You can find the latest Nvidia software here, and AMD's latest drivers here. AMD includes basic overclocking controls in the ATI Overdrive tab of your included Catalyst Control Center software; for an Nvidia card, you'll need to download the Nvidia System Tools utility to change your GPU clock speed settings.

Tweaking in the AMD Catalyst Control Center.
Open the utility for your card, and locate the clock speed controls for your GPU's processor and memory. AMD's Catalyst Control Center keeps them under the Overdrive tab; for Nvidia, the clock speed sliders are in the Performance menu. Now, just bump the sliders up in small increments--about 5MHz to 10MHz at a time. As with the CPU upgrade, tweak, save, reboot, and give the new settings a stress test by running free benchmarking software such as Heaven 2.0 or by playing a graphics-intensive game for 15 to 20 minutes to check for graphical corruption--that would be a warning sign that your GPU is starting to fail.

If you see solid blocks of flashing colors or strange flashing pixel formations, you've pushed your GPU too far; in that case, restart and roll back a few increments. Most contemporary PC components are sturdy enough to withstand this kind of tinkering. If you roll back to a stable overclock setting at the first sign of trouble, your components should be fairly safe.

Overclocking Your Memory

Yes, you can overclock your RAM, too. But make sure you have matching sticks of RAM (same speed, manufacturer, and so on) before you start messing with the memory. It's much easier (and safer) to buy more memory than to overclock what you have. But if you've come this far, "easy" and "safe" probably don't mean much to you.

First, open up CPU-Z and flip to the ‘SPD' (Serial Presence Detect) tab to look at your machine's memory specs. Reboot into the BIOS menu and select the performance menu-most likely labeled ‘Performance' or ‘Configuration', depending on your motherboard manufacturer.

Enter the memory configuration menu (it was labeled ‘Memory Overrides' on our test bed), and disable the default memory profile. Adjust your memory multiplier by selecting a preset overclock option or by typing in the RAM clock speed. Use increments, one or two at a time, that match consumer-grade products (DDR3 RAM is typically sold in increments of 800-1066-1333-1600-1867-2133); save the changes; and exit the BIOS. Stress-test as usual, and consider running memory-testing software such as MemTest.

To comment on this article and other PCWorld content, visit our Facebook page or our Twitter feed.
Shop Tech Products at Amazon
Notice to our Readers
We're now using social media to take your comments and feedback. Learn more about this here.