Overclocking the Radeon HD 7990
We spent a little time overclocking the Radeon HD 7990 to see what kind of additional frequency headroom it had left under its hood. For these tests, we used the frequency sliders available right in AMD's Catalyst Control center on the Overdrive tab.
Unfortunately, those sliders only allowed the GPU and Memory frequencies to be increased by 100MHz and 75MHz, respectively, which was no trouble from the Radeon HD 7990 at all.
With the sliders maxed out one the Overdrive tab, the Radeon HD 7990 ran with a 1100MHz GPU clock and 1575MHz (6.3Gbps effective) memory clock, up from the default 1000MHz and 1500MHz.
While we had the card overclocked, we re-ran a couple of tests and saw only marginal improvements in performance. We're sure there's more headroom left with the card, however, which may be tapped using a third-party overclocking tool that allows for higher frequencies than Overdrive.