Thanks to everyone for your help & comments.
ive ran a few tests using, Valley Benchmark. Furmark Graphics, prime 95 together with Core Temp, All results have came back satisfactory.
So further investigation shows it appears to be the Elgato capture HD60 device, When unplugged everything speeds up to what you would expect from this PC set-up.
So now I'm open to suggestions on a work around to prevent the later from happening as he still needs his Elgato capture device.