" The headroom on the GTX 590 is at this point limited to about a 10 to 15% margin over the as delivered clock speeds, Even though the card supports voltage tuning. The overriding theme of this card is cooler and quieter than the competition. I did not have an overclocking utility to push the clock speeds above the 10 to 15% margins until late last night. At this point the overclocked testing had been completed but ASUS came through with their latest version of their Smart Doctor utility to help us out. With the stock voltages the maximum speed I was able to pull from this pair of GF 110 GPU's was 673MHz or right on that 10% margin. The memory was equally stingy at 1868MHz or 934MHz. At these speeds there was a definite performance increase that was noticed so overclocking is worth the effort and time to find the maximum clock speeds."