Unlike the X-400FL on the review photos the P-400 does not come with dual mounting holes.
Interesting observation. Just checked the SPCR review of the 520W Platinum model (http://www.silentpcreview.com/article1313-page1.html
) and it also appears to have only one set of mounting holes.
Can't see any reason for such a design change to be made. A comment worth making on the 520W review perhaps? Can Seasonic provide design justification for this? It certainly makes installation in some cases less practicable.
I have contacted Seasonic support regarding this issue but since holidays are coming I don't expect reply anytime soon.
So what are you going to do with it then? A case mod to put screw holes in the right places is one option. Some cases already have 2 sets of screw holes for this purpose.
The case is definitely not moddable in that way with reasonable effort. The ATX mounting is asymmetrical and the back cover is only in places where required to fit the screws so in some places there is too much and in others it is missing.
Looking at the other case laying around it has the dual mounting allright but that case is a fail Chieftec which is too short to mount a PSU and a CD-rom at the same time. Also its drive cage extends into the space occupied by the CPU heatsink. At least the lack of vents below the PSU in the Chieftec case would not impede this one as it has solid cover on the bottom.
I guess looking for another case is an option and exchanging the PSU for the older revision is another. Will have to wait after holidays are over either way.