To overclock the AMD Radeon HD 6990 4GB graphics cards series, we used
Overdrive utility that is part of the CATALYST Control Center. When you
‘unlock’ the ATI Overdrive, you can manually set the clock and memory
The AMD Radeon HD 6990 starts off life at 830MHz on the core and
1250MHz on the memory. We were able to use AMD Overdrive and get the card up to 950MHz
core and 1350MHz on the memory and didn’t see any issues in the games
with PowerTune left alone. This is a 120MHz overclock
on the core and a 100MHz boost on the 4GB worth of GDDR5 memory ICs.
To test out the overclock we fired up 3DMark Vantage to see what this overclock was like.
The AMD Radeon HD 6990 Video Card Stock 830MHz/1250MHz:
The AMD Radeon HD 6990 Video Card Overclocked 950MHz/1350MHz:
Running 3DMark Vantage with the Extreme preset we got a
score of X18781 with the card at reference clock settings. The score
went up X20735 3DMarks when overclocked, which
was an improvement of 1954 points or 10.4% thanks to spending a bit of time overclocking.