To start with, I should note that my machine is a 2011 System 76 laptop.  I am currently running the KDE 5.5.3 backports to 15.010.  The machine has an nVidia card (a GEForce GTX 560M) and I use the nVidia proprietary driver.

I have long noticed that for some reason, Firefox (my preferred browser) makes the graphics card spin up all the time.  The slightest touch on the scroll bar, for example, sends the GPU clock to the highest rate, which causes the GPU to run quite hot and the fan to spin up.

To counter this, I add this to the xorg.conf

Section "Device"
     Identifier     "Device0"
     Driver         "nvidia"
     VendorName     "NVIDIA Corporation"
     Option         "RegistryDwords" "PowerMizerEnable=0x1; PerfLevelSrc=0x2222 PowerMizerDefault=0x3; PowerMizerDefaultAC=0x3"
     Option         "Coolbits" "9"
     Option         "UseEdidDpi" "FALSE"
     Option         "DPI" "96 x 96"
EndSection

This pegs the clock speed to its lowest level, which is fine except for watching videos.

So, when these powermizer settings are in effect WHEN THE MACHINE IS STARTING UP (!) and there is a full screen firefox open, konsole fails to reopen - even if the settings were not in effect when the machine was shut down.  It will often, though not always, fail to reopen even if konsole is the only thing on the desktop.

This is new to kde5 - everything was fine in kde4.

Now if I switch the setting so that PowerMizer runs at the middle level, the problem rarely appears.  And, as I have noted, it appears to matter the state of the setting when the system is starting up, not when it is shutting down.

I suspect that this has something to do with the switch to Wayland.  I would love suggestions as to how to debug this, so I can see what is happening as the new KDE session is starting up.


Reproducible: Sometimes