I think that 99.999% of PC users have no need in this kind of device, at least in PCI/PCIE-card form. As you know, many contemporary consumer CPUs consist of several cores, from 2 to 4, and their quantity will just grow (6, 8, 12 and so on). How do you think, is every CPU core working all the time? In almost all cases - no. So, I think, security software can work on one of those cores, leaving the others to other programs.