Just an update, I sent the PC back to PBtech last week Wednesday and they messaged me Saturday to say it was the PSU that’s at fault and have replaced and sent back pc to me today (should see it today or tomorrow)
I chose to upgrade to a NZXT C650 as it’s essentially a Seasonic psu.
I know PBtech have a muddy name with some here in terms of customer service and horror stories about warranties but I gotta say I’ve had all good experiences with the Christchurch branch and this is another one to add, I’ll definitely be back again. Kudos PBtech!
Huge thanks to all those who posted here with help. Really appreciate it.