My new PSU has a 140mm diameter fan, whereas the PC case has a 120mm diameter air vent over which the PSU fan is designated to sit.
Is this acceptable?
Why l'm reluctant to make a return:
It's a top tier PSU and l'm reluctant to return it, as l've already returned 2 items, each time because l wanted more juice and / or a better model (l've been a good boy, the first PSU had never actually been used). In the case of the 2nd PSU, l actually suspected a fault as well. But anyway, this time, l am extremely reluctant to do a return, due to the cost of return postage and packing, and the cost of any future PSU, as l feel it good manners to at least order a more expensive item if doing a non-faulty return.