You may no need to change your Desktop PC if it's GPU dose not meet your corrently need. You just need a 24 to 8Pin Dell Optiplex 3020 7020 ATX Power Supply Motherboard Adapter for Dell Optiplex 9020, Dell Precision T1700 to able upgrade GPU Card and other hardware.
ATX 24Pin Female to for DELL Optiplex 3020 7020 9020 T1700 Server Motherboard 8Pin Male Adapter Power Cable
DELL Optiplex 3020 7020 9020 T1700 Motherboard 8Pin Power
8Pin Compatible with for Dell H61/H81/Q77/Q87/B75/A75/Q75/Q65 etc motherboard
18AWG wire, support 1000W high power PSU
1x ATX Power Cable
Please allow minor deviation due to manual measurement.
Due to the difference between different monitors, the picture may not reflect the actual color of the item.