This thread shares conclusions of my research regarding the latest and older Gaming CPUs.
I hope it will complement CynicalCyanide's 'Guide to buying a PC' well for any PC enthusiast looking to build a new rig. (link below)
https://forums.robertsspaceindustries.com/discussion/15249/guide-to-buying-pc-gaming-hardware#latest
As a general guideline in choosing a CPU for Star Citizen, anything from Tier 3 and upwards should handle the game without seriously bottlenecking a modern gaming Graphics Card. Overclocking for Tier 3 CPUs is strongly recommended.
In the pre-Mantle/DX12 era, AMD CPUs of Tier 2 (and below) would benefit too from overclocking to gain fps when not running with Mantle API that reduce CPU overhead drastically and eliminate bottlenecking when paired with a high-end GPU.

Gaming CPU Hierarchy List (January 2014).

Tier 1
Intel
Core i7-4960X, -3970X, -3960X, -4930K, -3930K
Core i7-4790K, -4770K, -4790, -4771, -4770
Core i7-4820K, -3820, -3770K, -3770, -2700K, -2600K, -2600
Core i5-4690K, -4670K, -4690, -4670, -4570, -4440, -4430
Core i7-990X Extremes, -980X, -975X, -965X
Core i5-3570K, -3570, -3550, -3470, -3450P, -3450, -3350P, -3330
Core i5-2550K, -2500K, -2500, -2400, -2300
AMD
FX-9590, -9370, -8350, -8320

Tier 2:
Intel
Core i7-980, -970, -960, -950, -940, -930, -920, -880, -875K, -870, -860
Core i3-4360, -4350, 4340
Pentium G3458 (40th Anniversary Haswell unlocked)
AMD
FX-8150, -8120, -6350, -6300 -4350, -4300
A10-7850K, -7700K, -7800, -7600
Phenom II X6 Black Editions 1100T, 1090T
Phenom II X4 Black Editions 980, 975, 970

Tier 3:
Intel
Core i5-760, -750, -2405S, -2400S
Core i3-3250, -3245, -3240, -3225, -3220, -3220T, -3210
Core 2 Extremes QX9775, QX9770, QX9650
Core 2 Quad Q9650
AMD
FX-6200, -6130, -6120, -6100, -4170, -4150
Phenom II X6 1075T Black Edition, 1055T
Phenom II X4 Black Editions 965, -955, -940
Athlon II X4 Black Editions 760K, -750K
A10-6800K, -6790k, -6700, -5800K, -5700


Tier 4:
Intel
Core i5-680, -670, -661, -660, -655K, -650
Core 2 Quad Q9550, Q9450, Q9400
Core i3-2130, -2120, -2125, -2105, -2100, -2120T, -2100T
AMD
FX-4130, -4100
Phenom II X6 1055T, 1045T
Phenom II X4 945, 940, 925, 920
Phenom II X3 Black Editions 740, 720, 715
A8-6600K, -6500, -5600K, -5500
A6-6420K, -6400K, -6400, -5400K
Athlon II X4 651K, 645, 641, 640, 638, 631

Tier 5:
Intel
Core 2 Extremes QX6850, QX6800 QX6700
Core 2 Quad Q9300, Q8400, Q8300, Q6700, Q6600
Core i3-550, -540, -530
Core 2 Duo E8600, E8500, E8400, E7600
Pentium G2130, G2120, G2020, G2010, G870, G860, G850, G840, G645, G640, G630
AMD
Phenom II X4 910, 810
Athlon II X4 645, 635, 630, 620
Athlon II X3 460, 455, 450

*Intel Extremes or 'X' and Intel 'K'= unlocked CPU Multiplier
*AMD 'FX', 'K' and 'Black Editions' = unlocked CPU Multiplier
*Across Tiers, higher lines indicate more powerful cpus and models starting from the left of each line indicate the faster cpu model of that product range.

I intend to keep this thread updated till we start flying for real in the persistent universe of SC.
If you have any objections, comments or approves feel free to reply. Constructive criticism is always accepted.

Changelog:
May 2013
- Added AMD FX-6350, FX-4350
June 2013
- Added Intel i7-4770 and i5-4670 line of Haswell CPUs.
- Added AMD A10-6800K and rest of Richland CPUs.
June 2013 Update 2
- Added AMD FX-9590, FX-9370
- Added Intel i5-4570, i5-4430
September 2013
-Added Intel Core i3-3250, -3245
-Added AMD Athlon II x4 750k, -760K
October 2013
-Added Intel i7-4820K, -4771
-Added Intel i5-4440
January 2014
-Added AMD A10-7850K and rest Kaveri lineup.
March 2014
-Added AMD A6-6420K
May 2014
-Added Intel i7-4790K, i5-4690K etc.