該升級還是加一張獨顯即可?

以下為小弟之配備:請高手建議一下
System Information
------------------

System Manufacturer: ASUSTeK COMPUTER INC.
System Model: CM6870
BIOS: BIOS Date: 02/24/12 21:54:35 Ver: 04.08 (type: BIOS)
Processor: Intel(R) Core(TM) i5-3450 CPU @ 3.10GHz (4 CPUs), ~3.1GHz
Memory: 8192MB RAM
Available OS Memory: 8080MB RAM
Page File: 3294MB used, 6064MB available
Windows Dir: C:\WINDOWS
DirectX Version: DirectX 12
DX Setup Parameters: Not found
User DPI Setting: 96 DPI (100 percent)
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Disabled
Miracast: Available, with HDCP
Microsoft Graphics Hybrid: Not Supported
DxDiag Version: 10.00.17134.0001 64bit Unicode
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不玩線上遊戲，僅用模擬器玩手遊。請問大大們小弟該升級換電腦，還是買個顯卡來用即可，老電腦繼續撐?
組新電腦預算20k左右，單買顯卡<=4k
謝謝