elitedesk 800 g1

Hello, I have this build PSU: Corsair CX650M CPU: 17-4790 MOBO: 18e4 with h81 chipset ( it's from an old HP Elitedesk 800 G1 TWR) BIOS: 20.02.2020 RAM: DDR3 32GB (4X8) When I connect my RTX 2060 Super 8GB to the mobo with the PCIE express without the 6+2 pins connected from the PSU it turns on...