Sigh.
So, Raidmax is pretty horrible when it comes to the quality and performance of their power supplies. That might not be AS big of a deal since this is likely a very low powered system, but the amount of power the system draws is rather unimportant if the power supply itself is just simply problematic. In fact, Raidmax is definitely on my list of "don't use" models. They do have like one or two halfway decent models out there but they are not common, they are expensive and they are not THAT unit that you have.
Below you will find MY standard list of recommended power supplies and beyond that this thread is intended as a landing place for questions or discussions regarding specific units, platforms or related PSU tech, all of which are all welcome to be discussed here. If it's related to power supplies...
forums.tomshardware.com
Even so, if this unit hasn't seen much use it MIGHT be ok for use with a relatively low power draw configuration.
What kind of hardware is this system running?
What is the model of this system, if you know?
Is this some kind of small form factor PC, and that is why the PSU wouldn't fit? Because if that's the case then the system is likely not going to fit elsewhere either. uATX is basically the same as micro ATX (mATX), but, often companies like Dell and HP use boards from companies like Foxcon, etc., and have the boards made specifically for their proprietary systems and do things like flip the rear I/O upside down so that the PCI slots are at the top and the I/O ports are at the bottom, rather the other way around like most non-proprietary boards are. Or they have other proprietary connectors like goofy power plugs.
If the I/O is normal on yours and everything is a normal configuration same as any other micro ATX board, THEN you might be able to get away with moving things to a different case but depending on the hardware it might be better to simply find a same form factor replacement that is just newer and has the necessary connectors and will fit in place without having to move everything and buy a different case.
Again, knowing the model of the system and/or the PSU itself would help to determine that, or not.