4K with FC 5 ultra is 14 fps 1080p 55 fps.....all @ ultra...
That's a very GPU-bound pattern (pixels per second is the same with all three configs)...
Rise of the TR (2016 GAME) Internal bench does 30 FPS on BOTH 1440p and 4k WTF?
... But given that, it's probably worth checking out CPU-bound angles too.
This is absolutely not normal for the hardware you're using, and throwing more hardware at it isn't a reasonable solution. A properly functioning 4790 with fast RAM is still an excellent CPU for almost any gaming you might want to do on a 60 Hz display.
Some blogs say the game is effected by memory speed type and bandwith but will it cut my frame rates in half?
Close to half sometimes (if it's not dual-channel) but you're probably dealing with a bigger difference than that here. If it were single-channel DDR3-1066, that might get it close, but there would still have to be something else wrong on top of that.
So I think your i7 4790 is indeed the bottleneck (which might be a little surprising).
A better datapoint from that chart would be the 2600K at 93 fps. A 4790 is a touch faster than a 2600K, and yet the OP is seeing 30 fps. No.
* What are your GPU clocks with a game running?
* How are CPU and GPU temperatures?
* What are CPU and GPU utilization listed as when running FC5? What about RoTR?
* What are your RAM use and CPU utilization at idle?
* Are you seeing any performance problems outside of gaming?
* Are framerates stable, or inconsistent/hitchy? How's input latency?
I have not done a fresh install in the 3 years for fear of losing critcal data.
It's off topic, but that's worth fixing. No hardware lasts forever.