Normal
I have tested my i5-6500 + RX 470 (undervolted to ~120WTDP) with the HDplex 160W and also experienced reboots. My guess would be, that your system has power spikes over 240W (which is the over current protection limit of the HDplex 160W). This is what happened for me, even if the system showed pulling 200W from the wall.Try to lower the TDP of your GPU with e.g. Afterburner. Maybe that could be a temporary solution for you.
I have tested my i5-6500 + RX 470 (undervolted to ~120WTDP) with the HDplex 160W and also experienced reboots. My guess would be, that your system has power spikes over 240W (which is the over current protection limit of the HDplex 160W). This is what happened for me, even if the system showed pulling 200W from the wall.
Try to lower the TDP of your GPU with e.g. Afterburner. Maybe that could be a temporary solution for you.
