Stupid RAM questions.

[mcdj]

I recently bought 2x4gb Samsung RAM sticks for my late 2009 MBP 13" on ebay. The auction description said it was 1066MHz.

Installed the RAM, seems to work fine. Not really noticing a major difference between the new 8GB and the previous 4GB.

However, system profiler shows it as running at 1333MHz.

I googled a bit and people seem to be obsessed with cl9 vs cl7, whatever that is.

The questions are, is my RAM actually running at 1333MHz? Most people say it gets downclocked to 1066 in a MBP. Wouldn't the system profiler indicate the actual speed? And how can I tell if my RAM is cl9 or cl7? Finally, if it is cl9 and if the system profiler is wrong and I'm actually running at 1066, is there any performace hit with using the incorrect RAM?

Gracias.

mcdj

 

[GGJstudios]

Buying RAM
Matched RAM on Intel Macs
Understanding Intel Mac RAM

 

[mcdj]

alrighty then, thanks for the links, which answer zero of my questions.

Buying RAM
Matched RAM on Intel Macs
Understanding Intel Mac RAM

 

[tasslehawf]

You can always use faster ram, it will just run at the slower speed.

 

[vant]

CL7 is used by Apple for this round of laptops. If you computer turns on and runs stable, you are fine.

Also, your ram IS running DDR3 1333. It can take higher speeds provided the CL is 7.

You can always use faster ram, it will just run at the slower speed.

Not always.

 

[mcdj]

Also, your ram IS running DDR3 1333. It can take higher speeds provided the CL is 7.

Interesting. Thanks for the info. I'm still curious about how/where I see whether I have cl7 or cl9. It's not written on the chip that I can see, and system profiler doesn't specify.

 

[NickZac]

This is an interesting subject which seems to have, as you noted, two sides clash. I have read that higher speed RAM will generally run at the native speed.

Our conclusion is very simple: you get the best bang for the buck if you stick to the mainstream of the memory market, which currently is still DDR2-800 or 1066, preferably at low latencies. DDR3-1066 and -1333 memory do not yet result in better performance, and so should only be considered by hardcore enthusiasts, who aim for maximum overclocking performance knowing that they will get little benefit for spending a fortune.

It’s worth noting that DDR2 memory is amazingly affordable at its current pricing point. 4 GB kits look especially appealing, but remember that you’ll need a 64-bit operating system to take advantage of all of it.

http://www.tomshardware.com/reviews/ram-speed-tests,1807-15.html
It is a little bit older but I am a pretty big fan of reading their information. It may not apply today as the iX series and obviously the coming Sandy Bridge are not tested or discussed (they didn't exist then), so it is more of a basis than a solid conclusion.





Crucial, one of the memory experts for Macs, states that for the 2.53 13 inch MBP, the upgraded RAM have these specs:

* Drive Form Factor: 2.5"
* Drive Interface: SATA
* Maximum Memory: 8192MB
* Slots: 2 (2 banks of 1)
* Standard Memory: 4096MB removable
* USB Support: 2.x Compliant
* Although the memory can be installed one module at a time, the best performance comes from using matched pairs of modules.
Each memory slot can hold DDR3 PC3-8500 with a maximum of 4GB per slot.*

*Not to exceed manufacturer supported memory.

I would dare theorize that if there was a benefit to a different speed RAM, that Crucial would be recommending and selling that as opposed to the 8500