Here's the ATX motherboard form factor.

by R. Proffitt Moderator - 3/22/12 11:31 AM

In Reply to: New Motherboard for Viglen Incepta II by Ron6a has all the details about this standard so you can use that to see if this is an ATX case and if the mounting holes look OK.

My bet is you'll have to replace the power supply and rear I/O plate. Many motherboards come with the I/O plate.