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A guide to overclocking your CPU

Overclocking your PC is not quite voodoo, but can seem like it at times. Adjusting settings on your PC, video card, or other device in order to get faster or better performance is an incredibly nitpicky and time-consuming process that's often loaded with as much failure as it is with success. It's certainly in the realm of things that geeks do because they can. And although it's appealing to think that there is untapped potential in your PC's processor, in many cases the potential reward can be worth a lot less than it will cost you in time and possibly money.

Still, if you want your CPU to, say, crunch numbers faster, overclocking can be a more cost-effective route than buying new hardware. Think of it as putting multiple showerheads on your shower to get around water flow restrictions: It may be a pain, but if you're successful your PC will perform better than it did when you took it out of the box.

Why you should overclock

Whether overclocking is an achievement depends on why you want to do it in the first place. For many tinkerers, the only answer is also the simplest: "So I can tell my peers/rivals that I did it." Overclocking is a challenge loaded with risks and annoyances, and doing it well is often a source of pride – and bragging rights – for those who love building and upgrading their own computers. Surpassing the 5GHz or 6GHz barrier on a CPU earns you geek cred.

Others do it to get more performance out of their PC than they paid for, whether in the short or the long term. Their rationale is that they can get high-end CPU power out of a more budget priced part. (Car enthusiasts are also guilty of this type of behaviour all the time: "The manufacturer says I can go from 0 to 60mph in 10.6 seconds in this economy car. Let's see if I can fiddle with the engine and get that down to 6 seconds!")

Why you shouldn't overclock

There are also good reasons why you shouldn’t try to supercharge your CPU. The most obvious may be the results you derive. Upping your CPU's speed by 100MHz to 200MHz probably won't make your spreadsheets calculate faster. Always remember that overclocking can't do the impossible. It will never turn a two-year-old nettop into a 1080p high definition video editing machine, for example.

Then there's the question of cost. At the very least, running components at faster speeds will use more energy, and thus raise your electric bills. Purchasing additional accessories you need (such as a liquid cooler) could also put you out some dough.

More likely, you'll pay in time. Finding your system's ideal overclocked speed is a laborious process that can take hours or even days. If tweaking PCs is your hobby, that's fine, but if you're on the job the process of overclocking a CPU can take hours away from more productive work.

You may also pay the ultimate cost: Premature hardware death. Running your CPU or other components at faster-than-rated speeds subjects them to more heat and pressure, and may cause them to burn out earlier than they otherwise would. A good cooling system can reduce the likelihood of this happening, but you're still taking a definite risk.

Can you overclock?

If you think you want to try overclocking, you should start by determining what you can or need to do. If you're using a system from a major manufacturer (such as Dell, HP, Lenovo, Toshiba, or Acer), it probably has few or non-existent settings you can adjust; the best way to get a faster computer is just to buy a new one.

On the other hand, many boutique system vendors that cater to gamers and enthusiasts overclock their PCs at the factory, so you probably don't need to do anything else if you don't want to.

Once you know whether your PC is a good candidate for overclocking, you need to drill down further. Not all processors can be overclocked, and not all are overclockable to the same degree. If your processor was made by Intel and its model number ends with the letters K or X, or you're using an AMD processor in that company's FX series, it's unlocked. This means that users can easily modify the clock speed of the processor (make it run faster than it was designed or tested for), even with a stock motherboard. A so-called locked or stock processor can still be overclocked, but you'll have to have the CPU installed on an enthusiast motherboard with more settings to change.

If the words Core 2 Duo, Core 2 Quad, Athlon (sans "II"), or Phenom (sans "II") appear as the CPU in your system control panel or on your system's case sticker, or if your system originally came with Windows XP, 2000, 98, or earlier, your system is probably too old to bother overclocking (and will likely be more difficult than modern models).

Likewise, if you open your PC and are greeted by three-year-old dust bunnies and tufts of pet hair, don't overclock your PC. It's probably already stressed from all that dust and detritus, and it won't take kindly to any extra heat. If you've kept it clean with cans of air or an occasional vacuum, then give overclocking a shot – you know how to take care of you stuff.


Regardless of anything else, you shouldn't overclock if you're at all uncomfortable around technical procedures. Today's motherboard utilities make the process easier than ever, but any benefits could be outweighed by the sheer terror you'll feel if you misread a dialog box, click "OK," and lock up your PC. And needless to say, don't overclock the only PC in your house. If anything goes wrong, you may need another PC to look up a fix if you ever brick your overclocked PC.

If you're running a Xeon or Opteron processor along with a Quadro or FirePro GPU in your professional workstation, it's likely you need that power for a specific purpose. Don't meddle with overclock settings (aside from approved control panels that came with your system), because they have the potential to make your system unstable. An unstable workstation or a workstation that returns questionable results is about as useful as a humidifier in a rain forest.

Getting started

If your computer didn't arrive at your door overclocked, you can download and install programs for your motherboard that will help you adjust settings and monitor temperatures yourself. Visit the manufacturer of your motherboard's website to see if there's a download which is specifically designed for your hardware.

We highly recommend using the CPU-Z utility during the overclocking process. CPU-Z identifies your processor, motherboard, graphics card(s), and relevant settings and clock speeds for all three at any given point, so you're always aware of where your system currently stands.

If you want to go old school and do it the hard way, read up on changing the clock multipliers and voltage settings on your particular motherboard. If the preceding statement reads like an alien language to you, then go no further. Changing these settings without any regard to their consequences can lead to a locked up system at best, and a completely hosed and broken CPU at worst. Clock multipliers change the inherent speed of the CPU (i.e. the processor expends more energy, runs faster, and works harder), and changing the voltage settings will shift more power to the CPU or to components like memory. Changing the clock speed and/or voltage settings will make the PC work harder/faster/stronger, though at the increased risk of things going wrong or even burning out physically.

Veteran overclockers will tell you to eschew software and limit your overclocking attention to the BIOS or UEFI on the motherboard. However, recent software utilities do more than pay lip service to overclocking. The latest enthusiast motherboards are now intelligent enough to monitor the components to make sure you are really getting the overclock you paid for, as well as protecting the components from overheating, or being overpowered. Check your motherboard's manual for detailed information about these settings.

How to overclock

Okay, let's get down to the nitty gritty. Here's a generalised set of steps for overclocking your PC. Exactly what you'll need to do will vary according to the hardware you're playing with, and whether you're overclocking from the motherboard's BIOS (or UEFI) or if you're using a Windows-based utilities.

1. Start slowly. Begin by ramping up the processor's multiplier or "clock ratio" speed by one notch from default. Don't know what default is? Then you need to read the user manual. Though you can overclock the CPU and GPU separately with separate utilities, resist the temptation to boost the CPU's and GPU's clocks at the same time. Work on one, and then after you are done, move to the second. Changing more than one setting at a time is a recipe for disaster. If you set both to a higher level at the same time, and the system crashes on you, then you won't know if the GPU or CPU overclock is the problem.

Though tedious, it's best to write down the setting you just changed, every time you make a change. That way you know the last step to undo if things go wrong. Check if there is a universal default setting for your CPU and motherboard. You might lose your work, but if there's a backup panic setting, you can at least get the system running again in a pinch. Enthusiast-level motherboards like the Gigabyte GA-H87N-WIFI have dual BIOS setups so you can always fall back to the backup in case you overdo the overclock.

2. Reboot the PC. While the system is coming back up, watch for any error messages or problems. Does the POST screen report the components and speeds you expect? Is the computer booting slower than usual? If the system is slower, then you need to undo the setting you just tweaked. Did Windows start without issue? Then move to the next step.

3. Check that everything looks right. To ensure you haven't made a mistake, run CPU-Z and see if the clock speed settings are what you expect. If they look like what you were going for, you're probably in decent shape — at least for now.

4. Run a stability test. Even unstable systems can sometimes boot into Windows, so the only way to be positive you've not gone too far is to push your computer to its limits. AMD Overdrive comes with a built-in tool that will max out all of your CPU cores' performance capabilities, as do some of the motherboard utilities listed above. Other ways to verify stability include playing a game at the highest settings you've run before ,or running Prime95. Prime95 is a freeware app designed to find new Mersanne prime numbers. While that's a noble mathematical cause, Prime95 is also well-known as a common stress test for PC hardware, particularly the CPU. If the system is still up and running after 15 to 30 minutes, it's fair to assume it's stable. If at any point the system crashes or if you see garbled graphics on the screen, you've gone too far with your overclocking. Dial things back a notch, and try again.

5. Repeat. If your computer is still up and running, perform steps 1 through 4 again, changing one setting and one setting only. The setting could be system memory timing, a voltage setting, or even the rotational speed of one of the cooling fans. If the setting you changed didn't positively affect computation speed or game frame rate, turn it off and try something else.

Once you have the system running at the edge of instability, ramp the settings back one to three notches. That way you should have a stable, overclocked system that won't crash at an inopportune moment.

Upgrade your other hardware

With most systems, particularly budget models, you can only overclock so much before you hit a plateau. If that happens to you, a few targeted upgrades aside from the CPU may help you push speeds a bit higher.

Cooling. Heat is the enemy of any overclocker. If you're simply upping your system a few hundred megahertz (say, from 2.3GHz to 2.8GHz), then the stock air cooler in most systems should be fine. But for doing much more than that you'll want something better than the stock fan/heat sink that came with your processor or PC. This can be either a high-end air cooler or a liquid cooler (these are better for bigger systems you want to run at faster speeds), but it's essential: If you don't cool the processor or video card effectively, symptoms will include unexpected thermal shutdowns or physically overheating the processor. Cooling is one of the main reasons that overclocking is very rare on laptops: There isn't any room for additional cooling in most laptop chassis.

Power. Although not an immediate need for users simply trying to get one more year out of their PC, if you're overclocking to play games on your PC you'll need to pop in a new power supply unit (PSU). If your PSU is rated for 350 to 650 Watts, it should be able to handle light overclocking on its own. But if you're adding a liquid cooler, extra fans, and one or more enthusiast-level graphics cards, you'll need to replace that stock PSU with a more serious one that can drive 800 to 1,200 Watts.

Overclocking a PC is like souping up anything else, for example a car. You will get some added benefit depending on how much time, work, and money you're willing to devote to the project. If all you want is a faster PC, it may be easier to just buy a new one once your current PC seems slow. But if you're up to the challenge, you too can save some time when it comes to recalculating that huge spreadsheet after overclocking your PC.