I'm not sure in what context your refering to DMI, but if you mean Desktop Management Interface then it is completely unrelated to FSB or QPI.
FSB and QPI are channels which a CPU uses to talk to other components in your system (RAM, GPU, IOs).
FSB is found on old intel chips (core2 and older) and is a shared bus that connects the CPU to the northbridge and through which all data must pass.
QPI is found on the new core i* CPUs and offers a direct connection between the CPU and other components. Specifically it provides a separate channel from communication between the CPU and RAM.
The problem with FSB was that it created a bottleneck for all the data going to/from the CPU. With QPI offering a dedicated path to memory it significantly increases memory bandwidth.