I've got a Core i5-4690K @ 3.5Ghz, 16 GB ram, 250GB SSD startup drive, 4TB WD purple primary recording drive.
I'm running 13 cameras (2 old wifi samsungs, 10 Dahua 2mp starlights, 1 old hikvision).
I recently bumped all the Starlights up to 8192k max bitrate. Windows reports ~50-75 Mbps...