So for starters AMD have cheap multi core CPU's but their IPC (Instructions per clock) is slower than Intel's, thats why you can see a 4 core 8 thread Intel CPU beat a 8 core 16 thread AMD CPU.
CS:GO wants cores, but it likes to sap the juice from one of the cores the most. for example you can have 3 cores at 50% but one core at 100% which is a bottleneck.
Use MSI Afterburner, make all the cores visible in the On Screen Display and maybe post a pic.
But its probably just a slow core.
And again Im not an Intel fanboy I would love AMD to make better CPU's.
Games like faster cores, not more of them (most of the time) CS:GO wants both if you want 128+FPS
Also I suggest locking the game at 64FPS via RivaTuner because most of the servers are 64hz.