Checked the leads very carefully, I always try the kit out with the motherboard on the bench before I stick it in the case,anyway it seems to have cured itself,it's boot first time every time now,I noticed the problem occurs if I unplug the 240 mains lead from the power supply,once I got it to boot by repeated presses on the power button,it boots up first time after that,not the mains lead,tried a couple,tiz a mystery,I would have suspected the power supply,but the spare acted exactly the same.
Anyway seems to be ok now
Thanks for the help chaps.
