General mining query: Add2PSU power supply shutdown

So let's say I've 2 different sources of power 2 PSUs connected with an ADD2PSU. So PSU1 is connected to Wall1 and it powers the motherboard/cpu and GPU1. Now PSU2 is connected to Wall2 and only powers GPU2.

My question is if there is a power cut in the PSU1 socket (it shuts down the motherboard and cpu) and power on PSU2 is still available, will GPU2 still continue to run despite the system actually shutting down due to loss of power?

If PSU2 shuts down then it's all fine. If it doesn't do we have any potential damaging scenario for either PSU2 or GPU2?