I want to increase the RAM in my MacBookPro 15", 2.53 GHz, Mid-2009. I currently have 4GB, and I want 6GB (and upgrade to 8GB later – I think this should work with my model: http://forums.macrumors.com/showthread.php?t=573906)
Now I see two offers:
- 1x4GB DDR3 1333 CL9 9-9 (149 EUR)
- 1x4GB DDR3 1066 CL7 7-7 (192 EUR).
Both are from the same brand (Transcend), both are labeled "For MacBook/MacBookPro".
Now I have no idea, which of these would work better with the 2GB RAM module from my currently installed memory (Manufacturer: 0x80AD, Running at 1067 MHz, according to System Profiler – but with what CL setting?)
It's clear that both together will only run at 1066 MHz. But what about the latency?
- Would they both run with CL7? Maybe causing incompatibility?
- Or both with CL9?
-
Or would one run with CL7, and the other with CL9? Maybe causing incompatibility?
-
How can I find out the latency setting of my current RAM? (There's no BIOS screen on Mac. And System Profiler doesn't show it.)
I think I've read a few years time ago, that it's possible to decrease the latency setting for RAM, when running it at a lower clock rate (MHz). Would that still be true in this case?
Thanks,
Chris
PS Should I expect problems when I later upgrade to 8GB with a different module (in case the same module won't be produced anymore)? Is there a big risk, that two different modules won't work together very well?
Best Answer
According to Apple your machine has the 1066 MHz CL7.
http://support.apple.com/kb/SP544
HOWEVER Like the other answers say, higher RAM specs are often backwards compatible with slower mother boards ("logic board" in Apple's case). So you could go with the higher speed/lower cost option and do fine.
But I'd say that having a shop with a well known return policy might be better. Check the fine print.