Also use prime95, it stress tests much more harder, you will see an increase in temps as well as any errors with your overclock
Prime95 finds out errors much faster than OCCT and any other programs out there!
In my experience, OCCT took 8 hours to find the errors that can be found by prime95 in 40 minutes.
Furthermore, In place Large FFTs test
of Prime95 is the most trustful torture test.