Graphics       
                Video Adapter        NVIDIA GeForce GTX 550 Ti
                Video Memory        1.00 GB
                Screen Resolution        2560 x 1440
Central Processor       
                CPU Name        Intel(R) Core(TM) i3-3220 CPU @ 3.30GHz
                Code Name        N/A
                Manufacturer        GenuineIntel
                Current Clock Speed        3300 Mhz
                Max Clock Speed        3300 Mhz
                Voltage        4.6V
                External Clock        100 Mhz
                Serial Number        BFEBFBFF000306A9
                CPU ID        Intel64 Family 6 Model 58 Stepping 9
                Socket Designation        CPUSocket
                CPU Internal L2        512 KB
                CPU Internal L1        128 KB
                CPU Internal L3        3072 KB
Motherboard       
                Model        B75M R2.0
                Manufacturer        ASRock
                Serial Number                             
                BIOS Name        BIOS Date: 12/20/13 23:43:24 Ver: 04.06.05
                BIOS Vendor        American Megatrends Inc.
                SMBIOS Version        P1.60
                BIOS Date        2013-12-20
Memory Resource       
                Total Memory        3.94 GB
                Used Memory        3.58 GB
                Free Memory        376.72 MB
                Memory Usage        90%

사양이 이런데요.. 부품을 한개만 바꾼다면 뭐부터 바꾸는게 가장 가성비가 좋은가요?