https://bugs.freedesktop.org/show_bug.cgi?id=110865
--- Comment #14 from Alex Deucher alexdeucher@gmail.com --- (In reply to Dieter Nützel from comment #13)
Alex, is this the same problem?
No.
GFX Clocks and Power: 300 MHz (MCLK) 300 MHz (SCLK)
Your mclk is going to a lower state when it's idle.