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?
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?