It's not often I post to these forums with an issue of my own as I usually resolve them myself, but I need a bit of a sample set from MacBook Air owners here. I have a MacBook Air (Mid 2012), 1.8GHz i5, 8GB Memory with the 512GB Samsung SSD option. It's fast, it's efficient and it should be a brilliant machine. I don't use it for anything incredibly intensive in typical usage, but I do give it some stick every now and then, running some OpenGL applications, albeit ones dated back to 2004-2005 and therefore geared for hardware much older and slower than the equipment inside this machine. For the most part, it handles it all quite well. It gets incredibly hot in the process though. This is normal, but the figures are looking a bit on the high side. For example, the Intel Core i5-3427U processor has a listed TJunction Max temperature of 105C. This machine has been recorded at around 108C running these OpenGL applications, which the specs would have you believe is exceeding Intel's safe specifications for the Core i5 processor. However, the machine doesn't shut down. It continues running, just with its fans screaming at 6500rpm. CPU utilisation when running these applications is only about 35% at the most, so I'm inclined to think the heat is being generated in the Intel HD 4000 graphics processor portion of the core. In addition, when running an application like Safari without enough going on, such as a few videos playing in various tabs, the system doesn't heat up to anywhere near the above figures, but the entire system will hard lock up. Almost as if the graphics processor stopped responding. I'm thinking this could be Mountain Lion rather than a hardware issue as it seems to be most common in Safari and it doesn't appear as though I'm the only person with the issue out there. The OS has been clean installed with little difference. I work in an Apple Service Center and the general consensus is that I should probably request a Logic Board replacement. While the board is out, it wouldn't hurt to also polish the heatsink surface and use a higher rated thermal compound, such as Arctic Silver 5. I tend to agree with this assessment, having found it to be successful in lowering operating temperatures in the past, although I'm not sure the Logic Board replacement is necessary just yet. I'll have to investigate this further before making that decision. MacBook Air owners, answer me these... 1) What are your standard use (web browsing, iTunes) operating temperatures? 2) If you monitor temperatures, how warm have you been able to make your MacBook Air run? 3) Has anyone attempted to service their MacBook Air for better thermal efficiency before (thermal paste, heatsink, fan and so on), and what were the outcomes? 4) Has anyone's machine hard locked up when opening and using a large number of tabs in Safari, with or without video playing in any of them, or in any other application for that matter? When I read up about it, the issue does seem to be related to Mountain Lion, but it could be a combination of factors, such as the Intel HD 4000 driver for example (so it wouldn't affect all Mac models). Cheers, ~ M.