The 720BE is basically a 940BE that's clocked 200MHz lower, and has a core disabled.
For multitasking one would go with the 940, but for gaming the 720 is the way to go.
Here's a sample overview of what to go with based on your needs.
Gaming: 720BE + High-End GPU
Milti-Tasking: 940BE + Mid-Range GPU
For multitasking one would go with the 940, but for gaming the 720 is the way to go.

Here's a sample overview of what to go with based on your needs.
Gaming: 720BE + High-End GPU
Milti-Tasking: 940BE + Mid-Range GPU