Quad port nic cards choking CPU

acidsatyr

I have i7, 12 GB RAM, and i just got 3 quad port nic cards, together with 4 switches, for my ccie lab preparation.
I tried running vista, as well as windows 7 but same thing happens: when i install one NIC, my spu usage goes up to 30 %, and its staying there. When i install 2, it completely chokes it. What is the deal? Anyone have any clue where should i be starting my troubleshoot at all??? Drivers are all fine. I posted this on another forum as well, hopping to get as much input as i can, this is annoying.
thx

ccie15672

...do you have a loop in your ethernet network (with the switches you mentioned?)