Conclusion: It’s A Tie
ATI’s approach of offering an integrated overclocking feature (ATI Overdrive) right in the driver is a clever one, allowing users to squeeze additional performance out of their cards. As long as the fan speed profile isn’t completely off and the temperature thresholds are recognized correctly, driver-side overclocking should be sufficient. If you want to go beyond that, tools like RivaTuner and the ATI Tray Tools are for you. Offering practical features such as creating your own temperature-triggered fan speed profiles and a wider range of frequencies for overclocking, they will help you get the most out of your card’s GPU and memory.
Nvidia, on the other hand, doesn’t grant users the option to overclock its cards directly through the driver (you'll need to download the company's System Tools add-on). Instead, several card makers such as EVGA, MSI, Zotac, Asus, and Gainward program higher clock speeds right into their cards’ BIOS. If you own a card that runs at Nvidia’s reference speeds, we recommend taking a look at EVGA’s Precision tool, since RivaTuner no longer works with Nvidia’s current crop of reference drivers in its current 2.24 release.
The results of our individual tests underscore the impact a current driver has on performance. Indeed, upgrading to the newest driver allowed our candidates to turn out better performance numbers than when they were overclocked using their manufacturer’s modified (but outdated) versions, even at stock speeds! We keep mentioning this because, while a few board vendors do include some rather sophisticated O/C tools with their cards, these are often built into outdated driver releases, wasting their product’s potential where newer games are concerned. Even worse is that some features may be unavailable as a result. For example, MSI’s modified driver 8.542 wouldn’t let us run Far Cry 2 at 1680 x 1050.
When we compare our candidates at their respective stock speeds, ATI scores 398.3 total frames per second, while Nvidia comes in at 378.9 fps. Overclocking both cards to their very limit bumps the scores to 434.2 fps for ATI and 436.8 fps on Nvidia’s side. That means that overclocking the Radeon HD 4870 gives it a performance boost of 9 percent overall, while the GeForce GTX 260 sees a 15.3 percent performance improvement. If you go by the numbers, the GTX offers slightly more overclocking potential. Additionally, it has 1,792 MB of video RAM. On the other hand, it takes more effort to get those results out of the card, since you have to increase the voltage for both the GPU and the memory. And the twin fans run full blast when the card is overclocked to its limit, making it very loud.
In the end, what we have here is really a tie. Even when we look at efficiency measured in frames per watt, the scores are basically identical, coming in at 1.487 for ATI and 1.486 for Nvidia. In absolute terms, the ATI platform draws 292 watts compared to Nvidia’s 294 watts. Thus, whichever card you pick to overclock comes down to personal preference or, perhaps, whether you prefer CUDA or Stream.