Introduction

Whether you just built your first gaming rig, or you’ve been modding since the 8086, chances are you wouldn’t turn down the opportunity for a free performance boost for your PC. With the advent of jumperless motherboards and, more recently, Windows-based overclocking utilities that circumvent your motherboard’s BIOS entirely, CPU overclocking has been getting easier and easier.

On the graphics side however, not much has changed, software utilities for overclocking your graphics card have been around for years. In fact, in recent years the graphics market has taken a slight step backwards. The market is so competitive that few card manufacturers have been willing to take a chance and offer products that deviate from ATI or NVIDIA’s reference design, much less are overclocked from the factory. Only recently have a select few manufacturers really tried to break this mold.

That’s why when we first learned of ATI’s OVERDRIVE feature, we were excited about its potential. For the first time ever, a chip provider was offering a form of “safe” overclocking right in the video driver. This was a groundbreaking event.

For those of you who don’t know what OVERDRIVE is, we’ll provide a brief refresher. OVERDRIVE is a new feature unique to ATI’s “XT” line of graphics cards. When enabled, OVERDRIVE dynamically adjusts the core clock frequency of the graphics card depending on temperature. The cooler the core operates, the higher OVERDRIVE will clock the graphics core, but only to a point, 432MHz in the case of the RADEON 9800 XT (20MHz over default), and 527MHz in the case of the RADEON 9600 XT (27MHz over default). The intermediate settings are 419MHz for the RADEON 9800 XT, and 513MHz for the RADEON 9600 XT.

OVERDRIVE can be used in conjunction with third-party overclocking applications such as Rage3D Tweak and Powerstrip (more on this later). If one of these tools is used and the graphics core begins to exceed OVERDRIVE’s temperature parameters, OVERDRIVE will kick in and automatically reduce the clock speed of the graphics processor to one of the lower predefined levels mentioned above. If OVERDRIVE is disabled you can overclock your card to whatever frequencies you wish, but you won’t have the protection of OVERDRIVE.

Future versions of OVERDRIVE will include memory clock frequency adjustment, for now only the graphics core is overclocked. ATI will also include hardware monitoring functionality in the form of current clock speed and current temperature.

Like many of you probably were, we were initially a little disappointed once we learned OVERDRIVE’s final clock speeds, but we’ve always wanted to report our hands-on experience with this new feature. Today is that day.

After obtaining our initial OVERDRIVE results, we were even more let down -- the performance improvements we were seeing were even less than what we had hoped. We then set out to test OVERDRIVE with Rage3D Tweak when we discovered something: OVERDRIVE does not touch the memory’s clock frequency when overclocking! As a result, OVERDRIVE will reduce the graphics core’s speed, but the memory remains overclocked at our predefined level. Basically, we’re still getting the protection of OVERDRIVE, but we’re also getting most of the benefits of overclocking. After all, in the case of the RADEON 9600 XT in particular, the faster graphics core it boasts is begging for more memory bandwidth, more so than fill-rate.

We proceeded to run tests with all four configurations: stock clock speed, OVERDRIVE clock speed, all-out overclocked speeds, and OVERDRIVE clock speed with memory overclocked. Read on for the results!