Free your AMD: how to overclock AMD in 5 easy steps

Disclaimer
Overclocking has the potential to damage your CPU. However, the suggested settings in this article are extremely conservative, and in over a decade of overclocking we haven't damaged a single CPU. Having said that, overclocking voids your warranty (though it's impossible to tell if a CPU has been overclocked) and APC cannot be held responsible in the unlikely case of a CPU meltdown.

Recently we showed Intel users how to run a $250 i5 760 CPU at speeds that would make the $1,500 Intel chips blush. Overclocking is the name of the game, and this tweaker's pastime is a fantastic way to unlock the potential that lays untapped in most of today's processors. If you're an AMD user and were wondering why you weren't feeling any love, fear not, as today we'll be showing you five easy steps to make the most of your AMD CPU.



Overclocking AMD CPUs differs to Intel's range, but you'll still need a motherboard with basic overclocking features. Thankfully most mid-range motherboards include all of the necessary BIOS settings to squeeze the maximum MHz out of your silicon. Today we're showing AMD users how to overclock the AMD Phenom II line of CPUs. The AM3 965 Black Edition is a fantastic chip for tweakers thanks to its unlocked multiplier (every chip carrying the Black Edition moniker has an unlocked multiplier), making it much simpler to overclock than Intel chips. However, we're going to show you two ways to overclock your AMD chip, just in case you don't have one of the Black Editions.

Step 1 - Time to Chill Out

Just like Intel chips, or any processor for that matter, AMD chips get hotter the faster they run. Throw in slightly higher voltages to stabilise your new overclock and heat dissipation becomes your primary concern. Unfortunately the stock standard AMD heatsink/fan combo isn't hefty enough to handle the load, so you'll need to replace it with an overclocking thoroughbred. Based on recent benchmark results here in APC, the Noctua DH-D14 is hard to beat. It'll set you back just over $100, but considering it can help speed up your chip by 30% or more, it's an easy cost to justify. Once you've installed the new heatsink/fan, head into your BIOS (usually accessed by hitting delete just as your PC boots) and disable the Cool n Quiet option, which can mess with your overclocking settings. Reboot.

Step 2 - The Easy Way

If you're running a Black Edition, things are about to get really easy. Head into your BIOS. First we're going to give your CPU a little extra voltage; not enough to damage it, but enough to give it a healthy kick in the pants. As a general rule of thumb, a 10% CPU voltage increase is a conservative amount. Head to the section of your BIOS that shows the various CPU settings, and increase the CPU voltage (often referred to as Vcore - consult your manual if you can't find it) by 10% above its default value.

Reboot the PC and head into the BIOS again. Now you're looking for the CPU multiplier value. Increase this by 1, above its default value. Boot into Windows and start stability testing (see further details below). If it's 100% stable, head back into the BIOS and increase the multiplier by one more. Keep testing until you find your CPU's ceiling, then back it down one notch to obtain a stable, safe frequency. You're done!

Step 3 - The Slightly More Complicated Way

Welcome to those of you without Black Editions - bet you'd wished you'd paid the extra $40 now, right? Don't worry, you'll still get a healthy overclock out of your chip, it's just going to take a little longer.
 
Head into your PC's BIOS, and - just as we did in Step 2 - increase the CPU voltage by 10% above the default value (multiply the default value by 1.1 to find the new value). You'll also need to find the vChip voltage, often referred to as Northbridge and Southbridge voltages in more expensive motherboards, and increase their values by 10%.

Before we begin tweaking, it's wise to explain what the various busses are in your AMD system:

Reference Clock: All other settings reference this clock, including the CPU speed, the memory speed, the HT link and more. The default speed is 200MHz, which, when multiplied by the CPU multiplier, gives you the final frequency of your CPU. This is why increasing the multiplier is an easy way to increase the CPU's speed, as it doesn't impact the Reference clock, and thus all of the other subsystems remain within their default speeds. But if you're reading this step, you can't adjust the multiplier, so you're going to have to increase the Reference Clock, which will bump up the other areas at the same time.

HT Multiplier: The HT Multiplier value is a number that is multiplied by the Reference Clock, which then determines the speed of your HT link, a crucial system bus in an AMD system. The HT Multiplier usually has a default value of 5x; multiply that by the default Reference Clock speed of 200MHz, and you'll see that the default speed of the HT link is 1,000MHz. Therefore, as you increase the reference clock, you need to decrease the HT Multiplier, to keep the HT link running as close to 1,000MHz as possible. Make sense?

Memory Speed/Ratio/Divider: This works just like the HT Multiplier, but is used to determine the speed of your memory (either DDR2 or DDR3). Again, multiplying your Reference Clock by this determines the speed that your memory runs at. Therefore, if you increase the speed of your reference clock, you'll need to decrease the memory divider, to keep your memory running within its default speed. Hopefully you've got a motherboard that will show you the final speed of your memory as you adjust this setting - if not, we recommend heading to the web site of your motherboard manufacturer, and scour its forums for advice on setting the memory speed while overclocking. It varies greatly depending on each board, as well as the speed of memory you're running, and a guide on this alone could fill two pages.

Step 4 - Time to Tweak

Now that you know each of the major settings, it's time to start tweaking them. Your Reference Clock is the value you'll increase to make your CPU run faster, and start increasing it in 10MHz increments, starting with 210MHz.

As you increase it, change your HT Multiplier and Memory Speeds to keep your HT Link running as close to 1,000MHz as possible, and your memory running at its rated speed. After each 10MHz increase, it's time to do stability testing.

Step 5 - Stability Testing

After each 10MHz Reference Clock, it's wise to test the stability of your new overclock. Download a free piece of software called Stress Prime Orthos Edition. Run this for a few hours, and if your PC doesn't crash, repeat step 4 before doing another stability test. It's very important to do stability testing between each 10MHz increment, it will save you much more time in the long run.

Finally, try to complete a solid 12 hour Orthos run; if your overclocked CPU can do this, it's officially overclocked and stable.