I don't have the latest bios, I'm on version 308 exactly because I'm using ThrottleStop to undervolt it. This has been so for almost 2 years and the issues just started happening a couple of weeks ago.
Another thing I forgot to mention is that every now and again when the freeze occurs and I hard reboot the machine the keyboard stops responding - it doesn't light up and generally doesn't work. It has happened 3 times now. First time it started working after a shutdown. Second time I had to plug in an external keyboard and the native one just kicked in on it's on while I was using the other one. The computer was frozen a few minutes ago and the keyboard is dead again, still haven't recovered.
EDIT: 5 minutes after I wrote this the keyboard kicked in.