Question Is it safe to connect 24-pin PSU to Lenovo SFF M720e

[PaHa]

The OEM PSU used in this PC is 180w. with two sockets, one 4-Pin is for ATX_12V (two yellow and two black), and another one 5-Pin is for ATX-Power (two yellow, two black and one green). There is not any 24-Pin socket on the motherboard. I measured voltage in Power off /on condition.
Power off:
ATX_12V 4-Pin: 12V in 2 yellow lines
ATX-Power 5-Pin: 12V in 2 yellow lines and 3.3 Volt in green line.

Power on:
ATX_12V 4-Pin: 12V in 2 yellow lines
ATX-Power 5-Pin: 12V in 2 yellow lines and 0 Volt in green line.

Since I have an extra Crucial CV650 and RX6600, I want to upgrade my PC with them. The CV650 has two ATX 12V (4+4). Is it safe:

• To connect one of this 4-Pin ATX 12V to ATX_12V and another one to ATX-Power socket on the motherboard and get green wire from ATX 24 socket.
• To connect one of 4-Pin ATX 12V to ATX_12V and get 12V from ATX 24 socket to ATX-Power.

The voltage of green wire on OEM PSU has 3.3V but CV650 has 5V.
I am aware of not using CV650 and RX6600 in this SFF case I am going to use these externally.

 

[Eximo]

Corsair CV650

I have done things like that in the past, and there are pre-assembled adapters you can buy on amazon, ebay, or at moddiy.com

If you are swapping cases, at this point I would say just buy a new motherboard. You get away from the OEM board, which may not be suitable for long duration gaming sessions anyway and it will be easier to get a decent heatsink onto the CPU. RX6600 is going to demand a lot out of a CPU.