You will need to clarify exactly what board you have. That model either relates to a DDR2 only ASUS or a mix of DDR2 or DDR3 only boards that HP used in some of their systems. I can't see any boards with that model that support both DDR2 and DDR3.
Either way, I'd be very suspicious of whoever built the system, the ASUS board is significantly older than 2011 and the HP ones would have had to be stripped from an old system for you to have it, certainly doesn't look like someone building a machine from new, off the shelf parts.