I stumbled on this problem a week ago, i checked everything, i even changed the convertors and cables for it. When i open a game it just black screens sometimes not even at 70 degrees just pure black screen from the start. I did a stress test to find out and at 72 degrees black screened me, then i decided to up the power limit to 50 and to get the fans at 100% and it worked wonders, it reached 70 degrees but it was still running. I use a VGA-DVI D convertor and my psu is ATX 600W 20A which should be more then enough for the card. Anything can be useful at this point, beginning to be desperate.
This image was taken from a different website and gives OC percentage for your GPU.
Your graphics card is OC version. Therefore, you should try standard core speeds.
Standard core clock speeds of your GPU are as follows... 300 MHz, 588 MHz, 952 MHz, 1041 MHz, 1106 MHz, 1168 MHz, 1209 MHz, 1244 MHz
You should try to apply these core clock values with WattMan.
It's not an OC problem here, i tried underclocking it and giving it less and more power and the result was the same. Sometimes i can't even reach the lobby screen of a game because it black screens on the loading screen.
When you set power limit to +50%, GPU core power increases and TDP increases. And if the PSU is not good quality, GPU stabilization is reduced, 12V drops. So try to underclock without changing power of the GPU. Because this error is probably caused by WattMan.
I did lower the voltage from 900 to 800 and put everything that you told me on Memory clock settings, i only have 7 slots that i can write in the first one is locked to "N/A". I'll give it a try like this too see if the problem still occurs.
Edit: It's till happening, i can get into a game now, but when it starts it blackscreenes
Do not modify graphics memory values. Do not change the power. Just change core clock speeds. Reset WattMan before applying the change. I think this may solve the problem.
These are the setting that i made, i reached 75 with it, no black screen so far, if you have any tips of improving them, please do tell, i have no idea what i'm doing there but it works. The first one is with the new settings and the second one is with the default settings.
Voltage is low. 1000mV is very low. 1100-1150mV is ideal for the Polaris GPU. Never change memory or power. Because GPU may die over time.
Well, it got through the stress test but not the games, i'm still getting black screens. I think a better psu is a better idea then undervolting the card.
PSU change may be unnecessary. Follow this way.
Run Radeon Settings > Gaming > Global Settings > Global WattMan > Reset
Then click Frequency (%) and make this value to Frequency (Mhz).
And then enter these values to Frequency (Mhz).
588 MHz, 952 MHz, 1041 MHz, 1106 MHz, 1168 MHz, 1209 MHz, 1244 MHz
Do not make any other changes.
If the PSU is not enough, you will get an error in a different way. For example, the screen goes completely black.