PowerEdge 2950 GEN I with GEN II MB

I acquired some PowerEdge 2950 servers that are generation 1 chassis but have generation 2 MBs CU542 and DT021. they were pulled from a business that would not have upgraded the system boards and the installed CPUs are X5130. So would it be possible to add X5300 series CPUs even though the chassis is gen 1? is this a common occurrence? 

thanks,

P.