take some measurements, width, height, depth, as well as look at shape & screw/mounting points...
or if you can, take a pic of the PSU from back of case & from inside & post it, so we could look & see.
either that or someone else with a similar system might want to chime in on this?
as for me, I've only owned one "pre-built" system in the last 10+ years, & that was a $50 used HP Intel Celeron based unit I picked up a few years ago for a number cruncher for the old Find-A-Drug Distributive computing project.