Your CPU and GPU temps don't seem unusually high, but you say the freezing happens when the outside temperatures are 80+ F. I am assuming that this is a desktop system. When was the last time you gave the case a good cleaning? You could try to run the system with the side cover off as an experiment.
Someone mentioned to me that it could be memory failure, so I ran a memtest, but it didn't come up with any errors through 1 and a half passes.
To test your memory, I would recommend Memtest86+
, run either from a bootable CD or Flash drive.7 full passes
for minimal confidence, 12-24 hours
for moderate to maximum confidence, or until it registers an error
. If an error occurs, test each memory module separately to determine the culprit.