The reasons for this behaviour are many and various. Without your computer specification one cannot even start to guess. For instance, certain brands of intel processor protect themselves against overheating by just cutting out.
In other cases the power supply does similar things. We need as well as the dumps, (which may or may not prove helpful) your PC spec, including the make and power supply rating. Please supply all this. You may need to test memory and hard disc using free download programmes, and it would help us to give you suitable instructions if you told us how experienced you are with testing.