RAM for Early 2009 IMAC

Hi All,

I have a question about Ram. I've seen on the RAM chart provided by Apple that the RAM i need for my Early 2009 IMAC is

PC3-8500

(1066) DDR3

204-pin

SO-DIMM

I recently Purchased RAM I thought to fit these qualifications but I'm having trouble with it. (see specifications of what was purchased below) When I install both 4gb RAM modules i get a message saying my mac needs to restart. Once it booted fully but was acting very strange before it crashed. I tried installing one 4gb module with one of the existing 2gb modules and it worked fine. the mac was recognizing 6gb of memory. I'm not sure what the problem is. The RAM i purchases is:

8GB (2x 4GB) DDR3 SODIMM (204 pin) 1333Mhz PC3 10600 8 GB (9-9-9-25)

Is this the wrong ram and is most likely that one or both of the modules is faulty. Appreciate the help and insight. 🙂