I am a bit confused by your configuration data, specifically RAM. Is 24GB the Total RAM on the server? or is it just the Server Max Memory for the SQL 2008R2 instance? How much RAM did you reserve for the O/S?
It seems that all of the RG configuration is being implemented on the SQL2012 instance. Is that the case? If so, what have you done to control the default instance?
After all they are both using the same CPU and RAM.