You might want to stress test it a bit harder than that. I've never actually heard of "burntest" before. However, looking at the display, it only ran for 470 seconds? That's 7m 50s of "burn" hardly what I would call stressful. You'll need to push it longer to see if it and your cooler can keep up with the heat.
Unless things have changed, Prime95 is usually the go-to stressor for testing the CPU. Alternatively, you could give some assistance to medical research and run the Folding@home client on it.
I believe that is LinPack, which is a highly regarded stress tool for use in conjunction with Prime95.