You're 100% correct, it's an X4 860K. I haven't slept in almost 36 hours, that was definitely a typo I passed up lol.
It may be a slightly older architecture, but it's a quad core overclocked to 4.4GHz, and from what I could tell, even at stock clock rate it shouldn't bottleneck an R9 380 by more than a couple fps. Everywhere I searched said they are almost a perfect match as far as system balance goes. Ill see what I get with the default ultra settings, as I haven't actually tested with 1x renderRes.
Could you run Cinebench R15 on your CPU and post the single-core score you get? I`d like to compare it to my Xeon.
Running HD7950 on X5670 @4.15Ghz with HT off (so 4 cores effectively). Since my fav server is 1.7, i didn't bother using anything bar Optifine/Shader mod for 1.7.10
Regarding Continuum 1.2.1 (non PBR) I'm getting 18-20 FPS on 1080p render resolution (fullscreen), with 70-80% GPU utilisation and just one CPU core getting job done. Most likely my CPU is the narrow point here.
Minecraft, being a sloppy Java-based game, is really inefficient with CPU, this is a great example of heavy CPU-bound, single-core perf-dependant game.