Hi,

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 (Running at 1067 MHz, according to System Profiler - but with what CL setting?)

Would the 1333 CL9 RAM be set to CL7 when running at 1066 MHz?

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)?