Correct me if i'm wrong but it seems to me an i7 is a little overkill for 5-boxing, especially if you take care of the other bottlenecks:

- SSD
- RAM
- GFX card
- dual-boxing.com bookmark

I suppose some people can't live without 60fps and high settings on all screens but from a cost/benefit point of view, i7 just doesn't make sense.