Overclocking the Radeon HD 5700s
We were curious to see how much frequency headroom the Radeon HD 5700 series cards had left under thier virtual hoods, so for our next set of performance metrics, we spent some time overclocking the new Radeon HD 5770 and HD 5750 using the Overdrive utility built into ATI's Catalyst Control Center software.
In the end, we were able to take the Radeon HD 5770 up from its stock GPU core and memory frequencies of 850MHz and 1200MHz, respectively, to 950MHz and 1430MHz. We also saw gains, albeit somewhat smaller, with the Radeon HD 5750, which was able to hit 805MHz and 1170MHz, up from 700MHz and 1150MHz.
While we had the cards overclocked, we re-ran a couple of high-resolution benchmarks and saw increased performance from both. The increases weren't quite large enough to catch the Radeon HD 4890 or GTX 260, but the delta separating the cards certainly got smaller.
We'd also like to note that our Radeon HD 5750 acted peculiar while overclocking. We were actually able to pass the built-in ATI stability test with GPU clock as high as 860MHz, but games would crash almost immediately. Also, while the GPU was clocked that high, the memory had to clocked lower-than-default. Through lots of experimenting, we settled on 805 / 1170MHz, but think there's room for higher clocks with the card and that it was our particular sample that didn't behave well while overclocked.