My Mac keeps restarting itself part way through bootup
My Mac keeps restarting itself part way through bootup. Have tried safe mode, recovery mode and Cmd-option-P-R. but it keeps happening and I can get no further
Question marked as
yes to both the above. Also recovery and safe mode methods. whatever I try I just get the startup chime, the screen goes white and displays the apple logo with the progress bar below.
Soon as the progress is about 3/4 across the screen goes black, silent, and then starts all over again with apple logo and progress bar, this continues ad nauseam until I hard restart and fail another way.
Help
