also, mac hardware is usually not suitable for streaming, unless you are using a mac pro. the macbooks, and the imacs, all use mobile CPUs, which are generally not fast enough for HD streaming.
iMacs do not use mobile CPUs.
I'm not sure how that idea somehow got into your head, but if you do a little fact-checking you'll find that since 2009, baseline iMac CPUs have been: Core i5 (750), Core i3 (540), Core i3 (550), Core i5 (760), Core i5 (2400S), Core i5 (2500S), Core i5 (2400), Core i5 (3335S), Core i5 (3470S), Core i5 (3470), Core i3 (3225), Core i5 (4570R), Core i5 (4570S), Core i5 (4570), and Core i5 (4670).
Every one of these is an Intel "
desktop class" CPU (and this list doesn't even include the optional upgraded CPUs which of course are even faster).