@fribbledom When the ethernet cabling in the second room has an issue (like broken or swapped cables) you might get something lime that.
But you seem to have tracked it down to the power supply, so everything seems OK now 😉
We once had machines boot without issues in one room but with problems in another room. turned out it was the room lighting in one room that was emitting IR frequencies that interferred with the machines... Took us a while...