Created attachment 92344 [details]
journalctl crash log

Hello, I am back with something to report for my RV635/M86.
Like I said in comment 93, the crashes still occur, when using DPM.
I have now found a way to reproduce it (or rather - it found me).
I have just switched from using e17 as my DM to e18.
Now, in order to reproduce the crash I just have to use my desktop for a couple
of minutes and then it crashes. 
However, unlike before, the system can now recover from the crash. After about
a minute with the white screen, everything gets back to normal. Usually only
for a few seconds, and then I get the white screen again.
The experience is very stable when booting with "radeon.dpm=0".

I am using ArchLinux with kernel version 3.12

I have attached the journalctl output and I hope this can help you debug
things.