Laptop locking up

[mdmarmer]

My laptop is occasionally locking up completely.
it doesn't respond to anything when this happens
No response to keyboard or trackpad or Alt-Sysctl  RSEIUB -- nothing except power button
How should i start to debug this???
It does not seem to be overheating and all the hardware tests ok

It is Lenovo Ideapad 3 model 81WE.

[hendrikL]

Did you try the boot-parameter 'intel_iommu=igfx_off'?

[mdmarmer]

OK, thanks I rebooted with this parameter. Running ok so far.  I'll repost if it locks up again.