45c is a good temperature. CPU's overheat at about 80c+. My processor idles around 42c and hits 65c to 72c under full load.
Whether you think its overheating or not, it's a good practice to take the tower out (always outside as a cloud of dust forms) and using a air compressor or can of air to blow out the dust buildup, focusing on the CPU, GPU and PSU mainly. In high dust area's, its best to do this once a month, in lower dust area's you can usually get by with every other month, maybe even push it to quarterly. This will help extend the life of the system.