When you have full system crashes there is a very high chance it’s the graphics drivers, journalctl -b -1 might show some information why it crashes, as it’s often just the graphics output that freezes, not the rest of the system.
Another common form of crashing is just running out of memory. Linux still handles that not well at all and will just freeze for a long long long time (SysRq-F will invoke the OOM killer, which can often help and speed up the process dramatically, there are other workaround like earlyoom).