You don't
need an i7-6700K or <insert-current-high-end-CPU-here> to stream, but it can certainly help. I use an i5-3570K which works pretty well for
my purposes, but it would probably not work very well with newer high-demand games if I tried to stream at higher resolutions or framerates.
Similarly, number of cores doesn't much matter if the games aren't optimized for multicore anyway. If you max out a core, processes on that core are going to fight for CPU time and will likely suffer.
That said, all of this is rather academic.
@MissClickMaster said:
The Core2 Duo E8400 uses Socket LGA775. None of the processors suggested in this thread support that socket (except the Q6600, which is almost 10 years old and no longer supported by Intel), so you cannot
just upgrade the CPU. You would need a whole new motherboard at that point.
You
could get a
new Q6600 from NewEgg for $245, which is within your price range, but realistically, you'd be putting money into a system that very likely just needs fully replaced. In my opinion, you'd be better off saving that $250 towards a new system.