With the launch of the AMD Radeon HD 5870 graphics card fresh on our minds, we couldn't help but wonder how far we could overclock the card if we weren't limited by what Catalyst Control Center capped us at? Read on to see what we can do with the AMD GPU Clock Tool on our 5870 that comes stick at 850MHz GPU and 1200MHz Memory.

Wasting no time, we started ratcheting up both the GPU and memory speed. At default voltage, we were able to reach a maximum stable overclock of 935MHz GPU and 1280MHz Memory. This is a gain of 85MHz and 80MHz respectively. We were able to get the card to run at 950MHz but would lock up midway through the second 3DMark Vantage test. With a little more voltage 950-1000MHz should not be a problem on the ATI Radeon HD 5870...