To me either sounds like a faulty GPU or inadiquate PSU.
If the GPU works in a friends machine who has a better PSU at the default speeds then you know the PSU is to blame and without having to RMA the card.
I have 450Watt PSU, I had the geforce GT630 gpu in the past, which required almost the same wattage (about 60watt). can you confirm that it actually might be the PSU?, I have nowhere to test the gpu.
and by faulty GPU. is it possible to be physical damage? since the installation process was very sensitive, with safety rules followed. (if the chances to be badly manufactured GPU by the manufacturer)
U have solved ur problem? Got exactly the same....
Have you tried reducing the power limit? That is what it took for me to keep the display driver from crashing, or "resetting" all the time. I have set the power limit to -20.
I have also reduced the clock speed CEILING of the GPU from 1212 MHz to around 1000. I did not in an other way modify the settings, i.e. more voltage or less voltage etc. I completely understand that you are only asking to run what it says on the tin, you paid for the performance and you should have it.
In my case, I have simply concluded that my motherboard cannot supply the proper power through the PCI-E slot and therefore I must take performance down a notch.
(I have Dell Optiplex 990 from 2011 with Sandy Bridge Core i5-2500 and PCI-E 2.0 slot).
Question: is your Powercolor card drawing its power solely through the slot, i.e. no 6-pin connector? I have Gigabyte Windforce OC RX 460 4GB and it has no way to connect to external power.
Please see my response to moshi in the thread "RX 460 display driver crashes"