Thanks for the specs, there are no compatibility issues which is good, unfortunately there is no other way to find the PSU details without removing the side of the case unless of course you purchased the system from a supplier that has a website where the full specifications can be found.
Some information about the different types and sizes of PC case, its basic but you will get the idea;
http://en.wikipedia....i/Computer_case
To find the PSU details you must first shut down and disconnect any cables from the PC, remove the side, if you need to reach inside first take anti static precautions by touching a bare metal part of the case, write down the PSU details brand and model name or number and the power output, carefully reassemble your system and then post your findings here, let us know if we can assist with any of the above.