I've just done a system rebuild into a Coolermaster Cosmos 2. It's running great, cool and quiet.

I'm frustrated that there are no usb3 headers on the R3E board, and I really want to connect the front USB 3 on the Cosmos 2. Can anyone suggest a decent PCI-E card that offers USB 3 headers?

Also, this might be a stupid question; I'm running 3 x GTX 580's in the R3E. Would putting a 4th card in (the internal header USB 3 card) somehow change the bandwidth switching on the lanes?

Cheers