Currently Being ModeratedJun 18, 2013 2:45 PM (in response to Joe Batt)
If you are certain that the sticks you have are right for your machine and your are sure you installed them right then that's all that is left. It does happen.
What if you just put one of the new sticks in at a time, you might find that one of them is bad.
Currently Being ModeratedJun 18, 2013 2:47 PM (in response to Joe Batt)
There have been numerous threads on the forum with the same issue as you describe. A great many of those have involved PNY RAM. If still possible, return the RAM for a refund and purchase a different brand.
Currently Being ModeratedJun 18, 2013 3:33 PM (in response to Joe Batt)
Building on Franks suggestion, put in a new RAM chip and an original chip. If only 2 GB is recognized, the new RAM is incompatible.
Expanding on Stedman1's advice, the most reliable purveyors of Mac compatible RAM are OWC and Crucial.
Currently Being ModeratedJun 18, 2013 6:32 PM (in response to Joe Batt)
While you could test with a new and old stick installed there is really no reason to.
Just install each news stick in turn and see if the system boots. If it does then shutdown and try the other new stick.
Hopefully the system will fail to boot with one (or both) of the new sticks. In that case the non-booting stick is bad.
It gets a bit more complicated if the system boots with each of the new sticks but fials to bott with both.
Post back your results.
Currently Being ModeratedJun 18, 2013 9:40 PM (in response to Joe Batt)
I tried one stick at a time and it booted on one but not the other, so I guess it was a bad stick. Maybe its PNY from what has been said previously?
Now I bought these in the US and I am now back in the UAE (Brit abroad ) and memory is stupidly expensive here, so the next question is do I need two matched sticks or can I just buy 1 more 4GB stick and it will work with the PNY stick that works?
Currently Being ModeratedJun 19, 2013 5:37 AM (in response to Joe Batt)
Hi, i´ve been running my mbp with 2+8GB for about 3 months and never have a problem, give it a try, just check if the memory is compatible, i bougt a 8GB corsair with the apple logo, hope this help.