Core speed over core count wins every day as far as CPUs for gaming go. This has been true since the first dual cores came out, yet people still fall for marketing benchmarks. CryEngine-based games, like MWO, are strictly CPU bound on many rigs. Unfortunately, the high-end i7 you bought is great for multimedia tasks, but not so hot for gaming. You'd want the 6700K with its crazy overclocking potential.
Other than that, MWO's MSAA/TXAA implementations are pretty garbage, and tend to kill framerates. On a high-res monitor, AA can be disabled with limited impact on visual fidelity.
1. OC your CPU if possible.
2. Disable AA, postprocessing, and particles. Those options eat the most frames in MWO.
Source: Using a 4790K with a 390X @2560x1600, have similar issues. Things may improve under DX12, since it disperses driver tasks to all CPU cores, but there is no info on if/when MWO will support DX12. AA may improve if PGI notices CryEngine's built-in SMAA module (providing great AA fidelity/performance ratio).
Edited by Modo44, 10 December 2015 - 06:17 AM.