Overclocking Diamond's R9 270X was about as straight forward as it gets. With a lack of voltage control the only means of improving current flow to the core was by increasing the power limit settings. By maxing this setting out at +20%, I was able to boost the core clock speed on the Pitcairn-based core to 1190MHz - a 140MHz boost in clock speed over the default 1050MHz. Having worked with a couple R9 270X cards already, I had a good idea of where the core clock speed would end up, but each and every sample is different. Sometimes you get a (pardon the pun) "Diamond" in the rough. Memory overclocking also fell into the expected range. Based on the SK Hynix GDDR5 memory ICs used, around 1600MHz is a reasonable clock speed for the memory on this card from Diamond. This card was able deliver a 200MHz increase in the GDDR5 memory speeds over the as delivered 1400MHz. The boost of the memory clock speed to 1600MHz delivers a 6400MHz data rate versus the stock 5600MHz data rate for some help when the memory is your bottleneck. Keeping the card cool is paramount to getting stable clock speeds at higher than the rated capabilities of the hardware. Bumping the fan speed up to 100% helps cool the R9 270X down enough to bring stability at the clock speeds tested.