Might be a dumb question, but is the PSU s/w turned on , and set to 110v ?
Also if the PSU is located in the front of your case, sometimes the s/w arrives s from the mfgr in the off position. If that's so, you will have to remove the case's front panel to check it.
Thanks for the reply, have been through all of that. Am now in the process of boxing up the case and PSU to return can't return just the PSU. Will remember this next time an order separately.