Ok its i'm pretty sure now that zingle was spot on with the heat, had to run it with the sides off and put in an extra fan to keep the thing going.
Thing is only fan i had spare would only fit in space between the hdd and the side, not a problem if I run the thing with the right panel removed but if it put it back on it restricts the airflow to much and it overheats again.
http://www.fbdragon.co.uk/external/pics/PICT0243.JPG need to change that fan since it was one I recovered from a broken laptop cooler and is labelled as 5v and im probably got it on a 12v feed *although id have thought if it really was a 5v fan it would have gone pop on a 12v feed*
Could possibly fit a smaller fan on the front but I don't think that would work to well since the front vent is covered by the LEDs /pcb.
Was tempted to cut or drill some vents in the side panel (its only a thin aluminium) any case modders around that could advice?