REISUB basically does the same thing but slightly more gracefully. It will still reboot through basically any lockup (I have yet to encounter one it didn’t work on), but it gives your machine the chance to settle some things before cutting the power.

If a Linux machine locks up or freezes completely, use REISUB to restart it more gently than pushing the Power Button.

Hold down Alt and the SysReq (Print Screen) keys, and then type R E I S U B, with 2-3 second delays between the key presses to give the commands a better chance to complete.

R: Switch the keyboard from raw mode to XLATE mode
E: Send the SIGTERM signal to all processes except init
I: Send the SIGKILL signal to all processes except init
S: Sync all mounted filesystems
U: Remount all mounted filesystems in read-only mode
B: Immediately reboot the system, without unmounting partitions or syncing

source

I suppose if you wanted to be extra quick and liked living dangerously you could just do alt + sysrq + R + B (I’m assuming switching the keyboard mode is necessary for getting the other commands to work during a complete lockup, but I could be wrong, you might only need B). But I wouldn’t recommend it, REISUB is plenty fast for me.

There are other commands too, like alt + sysrq + F to summon the OOM killer.

Lastly, and perhaps most critically, it also feels way cooler than just holding a single button. Comme ça: