If your cpu passed the stress test at 80c, then you should be ok until you get a better heatsink. Few games get the cpu temps that high. And 45c is right on for the average idle temp. I've never seen any dramatic temp change with so called premium thermal paste, but that's just my experience. If you want to be safe, simply run the cpu at stock settings until your new heatsink arrives instead of removing it or changing thermal paste. The less you handle it, the better. I stopped running my i3 overclocked due to 2 dead ssd's, which windows gave me a temp warning in the task manager.