Hi Sathid,
The most common standard of PSU is called ATX, PS2 is a little more rare standard and used in cases with little space. You should look for a specific 'ATX' PSU
Well now I feel like a bit of an idiot lol. It fits perfect. The manual doesn't mention it but there it this tiny little removable corner bracket that you need to take out to install the psu. Absolutely NO mention of it in manual though....