Comment # 5 on bug 1103356 from Takashi Iwai

So you tested Leap 42.3 kernel on top of Leap 15.0 system, or tested the whole
Leap 42.3 system?  If the latter, please try the former; just install Leap 42.3
kernel on top of Leap 15.0 (with --force --oldpackage or whatever option), and
check whether the problem doesn't happen with it.

If the problem doesn't happen with Leap 42.3 kernel, then please try TW kernel.
 I checked the nouveau_hwmon code but there is no significant change, at least.
 So it must be really a high temperature due to some incorrect mode (no proper
power saving, etc).