Hi Redot.
OK, we can wait for the FW fix for the restart problem identified in the other thread, but I'm not sure it will fix your problem since your problem is with a shutdown.
I tested my 530 SSD on several systems and was not able to reproduce the behavior you are seeing.
I still think testing with a different monitor or by connecting your monitor to a different port (DVI, HDMI etc.) could be helpful in diagnosing this behavior. It may be normal for power to feedback through the Nvidia 2000, but is definitely not desirable.
I understand your point about the Samsung not having a problem. Hopefully understanding what is causing the behavior will allow us to understand why the drives act differently.