Yes, you can add this RAM.
Yes, you can add this RAM.
The system has four RAM slots, with two already using 2x8GB DDR4 sticks at 2133 MHz. You have two additional sticks from an older PC: one 1GB DDR4 and another 512MB DDR4. You can likely add them, but check compatibility and ensure they match the system requirements.
Noticing the mismatch, observe that the slots aren't aligned as expected. DDR4 uses a different slot arrangement compared to blue-green. The green connectors resemble DDR2.