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Overclocking

External Graphics Upgrade for Notebooks
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The ViDock’s Radeon 2600 PRO comes clocked at 600 MHz for the core and 500 MHz for the memory. We were wondering if the ViDock allowed for overclocking, and if so, how much performance would be gained from the endeavor, keeping in mind the limitations of the ExpressCard bus.

To that end, we fired up the overdrive option in the Catalyst Control center and forged ahead. To our delight, everything worked as it should; the 2600 PRO in the ViDock was happy to give us a significant overclock. The core went from 600 to 750 MHz, and while the memory wasn’t quite as accommodating, it did jump from 500 to 550 MHz.

With the overclock in play, let’s see what happened:

vidock expresscard graphics

The results are puzzling to say the least: the overclocked 2600 PRO managed to best both the 2600 XT and the 3870. While the 3870 was clearly somehow stunted in this benchmark, what doesn’t make sense at all is how the 750 MHz core / 550 MHz memory on the overclocked 2600 PRO beat out the 800 MHz core / 700 MHz memory on the stock 2600 XT. The chipset on the two cards should be identical.

While the slow PCIe 1x bus speed will definitely bottleneck the 2600 XT and 3870, it really doesn’t make much sense that the overclocked 2600 PRO would overtake them both, even by a small margin. We re-ran the benchmarks a number of times and reproduced the same puzzling results.

Let’s see what happens when the detail level is increased.

vidock expresscard graphics

At the shader-intensive medium settings, we see the 3870 has retaken the lead, but it is very closely followed by the overclocked 2600 PRO, which continues to outperform the 2600 XT!

We contacted Village Tronic to see if they had any explanation for this puzzling result; perhaps the ViDock drivers or hardware was in some way specially tied to the 2600 PRO it came with. They didn’t have any obvious answers for us, however.

Since we noticed this behavior at the end of our time with the ViDock, we didn’t have a chance to test overclocking with further benchmarks. But we will make sure that when The Asus XG Station is released and we compare ExpressCard video solutions, we will put more effort into investigating this issue.

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