One of the main factors that will dictate your 2D graphics score is your CPU base frequency. If you look at my passmark scores below you can clearly see this effect;
NOTE: All tests included the same DDR3 PC3-14900R (1866MHz) Ram, Samsung SM951 256GB UEFI boot, Quadro K4200, Tesla M2090, SanDisk Ultra II 480GB SSD, 4TB & 2TB HDD. Windows 7 Professional.
CPU base frequencies:- E5-2670 = 2.6GHz, E5-2690 = 2.9GHz, E5-2667 V2 = 3.3GHz
Editing 4K video is an extremely demanding task for any computer and I strongly recommend you check the minimum system requirements stated for your chosen 4K video editing software. e.g. AVID for example is coded in FP32 only therefore a graphics card optimized for FP32 should be used. Edius Pro and PremierPro have different system requirements.