Hello, the PD_12v_PWR connector is for additional power to support Quick Charge 4+ on the Front Panel USB 3.2 ports and USB Type-C. The ports will support 27W without the connector in place, and 60W when it's installed.
In terms of the GPU, I don't foresee any reason why performance or operation should be impacted by not installing it assuming all three cables are installed.
“The PD_12V_PWR connector provides additional power for your PCIe X16 slots. To support 60W, please install the power cable to the 6-pin PCIe Graphics Card connector (PD_12V_PWR) else only 27W will be supported.”
It’s a little unclear from the explanation in the manual. It has nothing to do with the stability of GPUs that require higher power like my 7900xtx?
So you’re saying this connector is unnecessary unless I require 60w quick charge, etc? If I do need it will a 4pin molex-6pin adapter be adequate to power it?
The connector is for additional PCI-E devices and won't impact GPU operation. Personally, I wouldn't worry too much unless you intend to use/charge USB devices that can make use of the additional current.