thanks T0SH this is a 24 way motherboards connector but it is definitely non standard now that I have the case open. The sata power leads for the hard drives must be almost 1m long. They go under the motherboard and come up between the two hard drives.
thanks all - having cleaned the inside of the pc it now works perfectly. I downloaded intels tat and it shows the cores working at 34 degrees and no problems apparent. I assume that eventually the fault will reoccur and then with luck I can fix it.
This thread is now locked and can not be replied to.