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Testing Methodology OverDrive and Overclocking: Not only is AMD releasing the new AM3 X4 Black Editions today, they are also announcing the release of AMD OverDrive 3. The AMD OverDrive utility promises to allow the user to easily overclock their CPU within Windows, as well as benchmark, stability test, and monitor their system's temperatures and voltages. It was not long ago that hardware manufacturers looked at overclocking with much disdain. As the overclocking community grew, however, many of these companies came to the conclusion that overclocking is something to embrace, not discourage. It almost seems ironic then, that AMD now provides the tools necessary to violate the warranties of their own products. For the purposes of our testing, we will be using the below setup:
What's New in OverDrive?
Click thumbnail for larger image The new AMD OverDrive keeps the same look and feel of the previous versions, but adds in some very intriguing features. The first of these features is the "Black Edition Memory Profiles", or B.E.M.P. for short. BEMP is essentially an online database between partnering module resellers which allow memory timing profiles to be downloaded from the internet and applied to the system from within the OverDrive utility.
Click thumbnail for larger image The BEMP feature allows manufacturers to specify timing parameters specifically for the AM3 platform, that may not be used by the SPD. On top of that, settings can be Imported and Exported, or users can create their own profiles using the following XML format:
Modules currently using the BEMP feature include the following:
Supported motherboards include the Asus M4A79-T Deluxe, Gigabyte GA-MA790FXT-UD5P, and the MSI 790FX-GD70. Another new feature of AMD OverDrive is called "Smart Profiles". Smart Profiles allows the user to set up how the CPU handles different applications, including setting the process affinity, as well as independent frequency adjustment for each core.
Click thumbnail for larger image The beauty of Smart Profiles is that you can assign the strongest CPU cores to run at their highest frequency without risking the instability of running the other cores at that same speed. In my mind, this in itself is a very exciting feature that allows for a whole new dimension of tweaking. Overclocking: Of course, the entire point of OverDrive is to help with the overclocking. The idea of an "Auto-Clock" utility is one with great promise, but for the most part, has fallen short of the capabilities of an experienced human and a well designed BIOS. The first few implementations of AMD OverDrive's AutoClock utility fits into this category as well, however, it is improving, mainly thanks to the new versions capability to recognize Black Edition CPUs and adjust the multiplier accordingly. In this case, OverDrive concluded the final overclock to be just under 3.9GHz at 1.45V. Under further stress testing, this speed did fail, however, it was close. Using the time-tested manual methods, I was able to get to 3.8GHz at 1.475V.
Another facet of overclocking I like to analyze is the voltage scaling of different architectures. It is common that as you approach your maximum overclock, the voltage needed to maintain stability tends to become exponential. Graphing the scale of stable overclocks versus the voltage requirement allows us to analyze where the sweet spot might be. In the case of the X4 955, this looks to be at 3.5GHz, which is a significant improvement over the X4 940, which hit its sweet spot fairly early at 3.2GHz. Of course, individual chips can vary, so who really knows how much of this is due to improved fab processes and architecture. The interesting thing here, however, is the fact that I had a difficult time finding stability at 3.9GHz at any voltage, even at 1.6V. This may be due to a temperature limitation, as I was hitting close to 55C with my Swiftech H2O-220 Compact water cooling setup.
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