Ok, given the stable, decent OC - you should have removed all but the slimmest bottleneck. If I were you, I'd attempt to get your 290 fully operational and use your current setup until Zen is released & you have options - assuming your current setup performs to an acceptable level for you today (290 heat issue excluded, of course).
If it simply boils down to you not liking the performance (from a CPU standpoint) and you're comfortable with the cost of an Intel upgrade, then certainly go for it. A n i5 setup, continuing to use your 290 in the meantime (assuming you can get it running at decent temps) would be a better performer than the 8320 - and you'd be perfectly placed to pick up a 1070 in the near future.
Dizzlepop11 :
https://www.youtube.com/watch?v=_du7O6-QD8Y
Here's a video of somebody with the same specs as me getting 60 - 120 FPS in BF4 at the highest settings, while I struggle to achieve 60 FPS most of the time, which leads me to believe that it's mostly a thermal issue. I should also mention that my GPU's cooler is zip-tied on, because it broke a while ago... (which has nothing to do with the thermal issues, because it was getting hot before it broke)
That video is 18 months old at this point, so you're not comparing apples to apples. You may well have a driver issue and should address that.
I may be misunderstanding here, but are you actually monitoring CPU/GPU temps? Or making an assumption of poor thermals for your lower performance? If you are monitoring, what program are you using?
For AMD CPUs you should be using AMD overdrive and monitoring the 'thermal margin'. Assuming you can stay in the safe ~10+'C (thermal margin, as in 10'C to shutdown) during stress tests, your issue probably isn't thermal related.
Of course, please correct me if I've misunderstood.