It is not clear to me if your cpu needs upgrading or the graphics card.
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To help clarify your CPU/GPU options, run these two tests:
a) Run your games, but lower your resolution and eye candy.
If your FPS increases, it indicates that your cpu is strong enough to drive a better graphics configuration.
If your FPS stays the same, you are likely more cpu limited.
b) Limit your cpu, either by reducing the OC, or, in windows power management, limit the maximum cpu% to something like 70%.
Go to control panel/power options/change plan settings/change advanced power settings/processor power management/maximum processor state/
This will simulate what a lack of cpu power will do.
Conversely what a 30% improvement in core speed might do.
You could also experiment with removing one core. You can do this in the windows msconfig boot advanced options option. set the number of processors to less than you have.
This will tell you how sensitive your games are to the benefits of many cores.
If your FPS drops significantly, it is an indicator that your cpu is the limiting factor, and a cpu upgrade is in order.
It is possible that both tests are positive, indicating that you have a well balanced system, and both cpu and gpu need to be upgraded to get better gaming FPS.
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If you come out thinking the graphics card should be replaced, make it a big jump or you may be disappointed if you don't see big results.
Think a $330 class card like the GTX970.
I would avoid the R9-290X cards, as they are older tech and seem to have issues.
If you replace the cpu, you will also need to replace the motherboard.
Intel of some sort is the only way to go .
Buy a Z97 based motherboard and a i3. i5, i7 of your choice.
For gaming, the $225 i5-4690K is as good as it gets.