Dragon Age scales really well with CPU performance. A single-core CPU will be fully utilized to the extent of holding back the graphics card. A dual-core CPU will be fully utilized as well. But despite this fact, you'll only see slightly better frame rates. With four cores, the load is more evenly spread out, and the graphics card can stretch its legs. Yet there's still a small performance increase when overclocking the CPU. The game seems to be CPU-limited, as indicated by the 90% graphics card utilization. Most likely, it would need even more CPU performance to increase that utilization number to around 100%.
This game uses up to 630 MB of graphics memory with AA enabled.
For best performance, you definitely need a quad-core CPU.