Problems with a Desktop Dell

[David]

Thanks Ben the only other thing to be tested is the PSU if its not that I will assume it is the MB and just get the data from the HD then move on

[Steve]

Just a point , I might be stating the bleedy obvious but you don't need to place the new PSU in the case to test it.

[Polchraine]

I would NOT change the drives over from one machine to the other but get a set of cables and install the drive from the problem machine as a slave on the working machine.    At that point you should be able to see some of the data.