More recently introduced terms such as 'annually laminated' are synonymous with varve. Of the many rhythmites in the geological record, varves are one of the most important and illuminating in studies of past climate change. Varves are amongst the smallest-scale events recognised in stratigraphy.
PCs are designed to shut down automatically when heat endangers the hardware. To find out if this is your problem, download and install Speedfan. It's small and free. Although Speedfan's basic job is controlling the speed of your PC's fans (you probably guessed that by the name), it also provides the CPU temperature.
You maybe working on an important project and your PC keeps shutting down randomly every 15 minutes or so. You hit the restart button and then it turns on again. Computer keeps shutting down is not a healthy sign. You need to carry out some simple diagnosis that helps treat the problem. Let us have a look at some of the causes that explains why your PC keeps shutting down randomly.