well it is at least 9 years old and started to fail first time on startup. So went into the BIOS and the CPU (central processing unit ) showed the cooling fan on the CPU was running slow. Time for a stripdown for a look see.
So computer front cover off- CPU fan and cooling unit unbolted from the mother board and also fan unplugged from mother board. Right now the unit was out detached the fan from the actual unit and there was the problem. 9 years of dust in the grid somewhere I could not get to with the unit installed. next blow out dust and clean fan then reassemble
quite a big lump to take out, never done it before but managed it quite easily