My system uses an Intel Core i5-2500K Sandy Bridge 3.3GHz 6MB Cache, LGA 1155 processor. A few days ago I saw a popup from the system tray, warning me that the CPU temp had reached 70 degrees C. I opened the case and found that the Intel CPU cooling fan was full of dust and debris. I replaced the cooling device, adding some thermal grease. After a reboot, the CPU temp in Bios was reported a 47-48 C. Today, the popup warning about 70 C happened again. Using a Windows application called RealTemp, the CPU temp was reported as 68-69 C. However, terminating a Windows process, which uses a lot of resources, reduced the temp to 40 C. I have run this process hundreds of times over the years without a CPU temperature warning. Wondering what I must do?