http://openhardwaremonitor.org/
What is nice about the app, is that you can start a web server, and connect from another machine. So even if a thermal shutdown or other crash occurs, you can see what the various monitor values were at.
This app is quite useful. I started using it to keep tabs on my system temperatures. This R9 290 causes the environment temp to soar, which freaks the CPU out and causes a thermal shutdown. I’ve ordered a Corsair H105 for the CPU so long, but while I’m waiting for it to arrive I’ve got a large floor fan sitting on my desk, blowing in to the chassis. With it running, the CPU reached a max of 64.6C, with the GPU reaching a max of 76C.
I tried running an app called HeavyLoad which comes up at the top of the results for a search on “stress tester”. It has the option to load your CPU, GPU, etc. While running, the load averages shoot up to 100% according to the monitor, but the temperatures don’t climb too much. It’s only games that seem to really stress the system and cause the high temps.