My computer is a Core i7 920 with 24 GB of RAM and a EVGA GTX 580 with 3 GB and 2x SSD in RAID 0.

With this machine, I can 10-box just fine. Though, I do have to turn down my graphics to the lowest setting and set the foreground FPS to 30 background FPS to 10 in isboxer (biggest performance gain for me).

I experience very little lag and it runs very well and I even have view distance turned up to high on all clients.

My main limitation seems to be CPU. if I had a 990x, pretty sure I could bump up the FPS and graphics a bit.