Summary: One of the key additions to ATI's "XT" line is OVERDRIVE, ATI's new utility that offers automatic overclocking. Initially end users were skeptical of OVERDRIVE, as the clock speeds were a bit on the conservative side. Just recently however, we've discovered that due to a slight bug on ATI's part, OVERDRIVE can be manipulated to offer performance comparable to high-end overclocking. Read all about what we learned and see the performance gains we witnessed as a result in this article!
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!
SIDEBAR: ATI will be holding an online chat session with Rick Bergman tomorrow, you may want to check it out!
Call of Duty (custom demo)
Nascar 2003: OpenGL
With all the physics calculations that must be performed for a game as intense as NASCAR Racing 2003 Season (which has a very realistic driving model) as well as AI and graphics, there isn’t much room left for graphics. However, at 1600x1200 we can see that the added bandwidth provided by overclocking the memory yields an extra 5% for the RADEON 9800 XT, and 8% for the RADEON 9600 XT. Performance is practically indistinguishable between the all-out overclock and the OVERDRIVE/Rage3D Tweak combination, which doesn’t overclock the core as much.
IL-2 Sturmovik: FB: OpenGL
IL-2 is another simulation that really stresses CPU performance rather than just focusing on graphics, as a result we see less of an improvement from overclocking the 9800 XT’s graphics core in addition to the memory. However, the 9600 XT’s performance is increased by 10% at 1600x1200.
Quake III - OpenGL
While it’s the oldest game in our testing suite, Quake 3 is still a great tool for comparisons as it can pick up the most minute hardware changes. While the other titles show little or no difference between the OVERDRIVE/Rage3D Tweak combination versus all-out overclocking, we can see clear differences in Quake 3. And with the right custom demo, Quake 3 can still be taxing on today’s latest hardware.
Unreal Tournament 2003 – Direct3D
With UT2003, the margins are pretty significant at 1600x1200 for the 9600 XT (11% going from stock to OVERDRIVE/Rage3D Tweak), but we’re looking at unplayable performance. The 9800 XT isn’t quite as starved for bandwidth, so it’s performance enhancement is a little tamer.
Splinter Cell – Direct3D
Tomb Raider – Direct3D
In the case of Tomb Raider, the 9600 XT really shines at 600/340, the OVERDRIVE/Rage3D Tweak combo isn’t as effective as it has been in previous tests.
Call of Duty
If you followed the Quake 3 benchmarks, you’re probably not too surprised with what we’re seeing in CoD. If you’re a heavy Call of Duty player you will probably want to go ahead and manually overclock your graphics core and memory.
Call of Duty 4xAA 8xAF
So there you have it, ATI’s OVERDRIVE feature isn’t quite as bad as you initially thought now is it? Thanks to an oversight on ATI’s part, you can get much of the performance improvement you’d normally get from overclocking by simply enabling OVERDRIVE and manually overclocking your memory with a third party tool such as Rage3D Tweak or Powerstrip.
By going this route, you get thermal protection for your graphics core, while at the same time you get enhanced performance. Sure, the performance boost it isn’t quite as high as what you’d see from maximum overclocking, but it’s an interesting option for those of you who would like to dabble with overclocking without getting your feet too wet. If you want all-out performance though you will want to stick with traditional overclocking.
We can’t help but feel better in regards to OVERDRIVE’s performance as a result of our findings today. It would actually be nice if ATI’s driver team left things as is in regards to the memory subsystem, and just added hardware monitoring functionality to the driver, because we have a nagging feeling that ATI will play it conservative in terms of memory frequency adjustment in future CATALYST driver revisions. What do you think?
In any case, if you happen to stumble upon someone talking noise about OVERDRIVE, politely remind the person that this is an available feature that can be toggled on and off. It’s not like ATI is forcing OVERDRIVE on its users. Think of it as a nice toy you can play with if you desire, we certainly do. And don’t forget to point them to this article – in many cases OVERDRIVE when configured to run with a third-party overclocking utility, can deliver performance that’s comparable to a maxed-out overclock! Who would’ve thought ATI would deliver something like this six months ago?
SIDEBAR: Were you as surprised by our OVERDRIVE results as we were? How have have you overclocked your RADEON 9800 XT card? Share your experiences in the news comments!
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