I have a 2011 iMac A1312, 12,2 27 inch LCD running El Capitan without any obvious operational issues. I am aware that this model has a long history of overheating issues. I have the AMD Radeon HD 6970M, 1GB video card which I have been monitoring with Macs Fan Control software. All hardware temps are normal except the GPU diode which idles at 50 degrees C, and 60 degrees C when doing normal internet surfing....and as high as 70 degrees C when streaming video. The 70 degree C reading concerns me, it appears to be too hot. So I may need some help here, assuming there is a problem.... First ,I will look inside the machine and clean out the dust and dirt from the vents, fans and heatsinks. I will then button it back up and see if the cleaning process improved the temps....if so, that may be the end of it! If not, I will be asking for more input on how I should proceed. My gut feeling is the high temps are the result of the thermal paste breakdown on the video card since the machine is 6 years old. At this point... there are no screen issues or artifacts. I am thinking seriously about removing the logic board and video card from the case and installing new thermal paste on the video card and the CPU. I am confident that I can do this even with all the connectors on the front and back of the board. Does this make sense or am I making a problem where it doesn't exist? Anyone have any comments or suggestions at this point?