I THINK I HAVE SPOTTED IT.
It looks like the 'professional wiring' job is to blame.
Next to the CPU in the top left, is a great big lead and a big socket that is marked 'ATX12V' - the connector is not in straight, it is kind of half pulled of on one side. The lead leads straight to the PSU - coming out of the PSU are loads of similar leads that have a plasic 'tie' around them.
It looks like when they put the PC together - they added the plastic cable 'tie' afterwards - basically, I think when they wrapped it around the 2 inch thick mass of cables and tightened it, it pulled the 'ATX12V' plug away from the motherboard connector.
I had a quick go trying to push it back in but it doesn't seem to want to budge - which makes me think the cable 'tie' is the reason for this - they probably did connect this thing, but the 'professional wiring' guy, dislodged it afterwards.
This explains the intermittent fault and why, when I laid the PC down on it's side (mobo facing up/plug facing down) it booted.
I'm going to email CyberPower to say I am going to have to cut the 'tie' off from around the PSU cables, to be able to push this ATX plug thing back in.
It looks like the 'professional wiring' job is to blame.
Next to the CPU in the top left, is a great big lead and a big socket that is marked 'ATX12V' - the connector is not in straight, it is kind of half pulled of on one side. The lead leads straight to the PSU - coming out of the PSU are loads of similar leads that have a plasic 'tie' around them.
It looks like when they put the PC together - they added the plastic cable 'tie' afterwards - basically, I think when they wrapped it around the 2 inch thick mass of cables and tightened it, it pulled the 'ATX12V' plug away from the motherboard connector.
I had a quick go trying to push it back in but it doesn't seem to want to budge - which makes me think the cable 'tie' is the reason for this - they probably did connect this thing, but the 'professional wiring' guy, dislodged it afterwards.
This explains the intermittent fault and why, when I laid the PC down on it's side (mobo facing up/plug facing down) it booted.
I'm going to email CyberPower to say I am going to have to cut the 'tie' off from around the PSU cables, to be able to push this ATX plug thing back in.