I was quite shocked when I tested the GTX 260 Black Edition against the HD 4870 for power consumption. The GTX 260 idled at 158 watts while the HD 4870 idled at 181 watts. It’s a well known fact that the reference HD 4870 512MB has terrible idle power performance due to the GDDR5 not downclocking appropriately but the load results were equally shocking. Since the GTX 260 core was so massive I figured it must naturally use more power. I was quite surprised when I measured 267w @ load for the GTX 260 and 271w @ load for the HD 4870. The fact that they were even within 10w of each other was astounding.
Considering how the GTX 260 Black Edition already has a significant overclock I wasn’t expecting much in the way of overclocking headroom. That being said, the results were incredible. I was able to get the core up to 739MHz, the shaders up to 1557MHz, and the memory up to 1285MHz. This was a 73MHz core overclock, 153MHz shader overclock, and a 286MHz memory overclock.