Non-Unibody, Core Duo & Core 2 Duo Processors

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A1261 Early 2008 Upgrade RAM questions

Hello. I Have questions on RAM upgrades. I Have Macbook Pro 4.1 (early 2008)

  • Core 2 Duo 2.6 Ghz
  • RAM 4 GB 667 MHz
  • LCD 1920

There is no answer if you can put in 2x4 GB RAM SO-DIMM's. And, why the system bus is 800 MHz yet the memory is 667 MHz?

Update (11/06/2017)

Can I insert DDR2 6400 800 Mhz SO-DIMM's?

FSB SPEED 800 MHz, Why Apple need 667 MHz RAM?

Yes, I have 2 slots of RAM, but Unoficial max is 6 GB.

Scott do you know this model?

Update (11/06/2017)

Yes ! This is my Computer.

Why 6 GB max for RAM not 8 GB?

Why 667 MHz PC2-5300 not 800 MHz PC2-6400 ?

FSB is 800 MHz.

Update (11/06/2017)

On forums I have read that the system detects 2x4 Gb only have problems with filling. The system fault above the given size pops up .. Did you hear anything about it?

Answered! View the answer I have this problem too

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To answer your questions:

- Why can't I go to 8 GB of RAM?

The reason is memory addressing. The memory address in this series is fixed for the GPU so the upper lines are in use. While you can put in a second 4 GB module you won't be able to use it (apps can't see it)

- The systems Front Side Bus (FSB) is 800 MHz so why can't I go with faster RAM?

The reason is the FSB is not the memory bus. Over the years the architecture of how a system is designed has changed. When this system was designed a FSB was used, today its no longer used as better designs are used.


As I stated a second 4 GB stick will be seen by the system profiler but the address lines to the upper RAM are used by the GPU so your Apps can't access this RAM. Not worth it stick with a 2 GB and 4 GB stick and call it a day.


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This appears to be your machine:

Apple MacBook Pro "Core 2 Duo" 2.6 17" (08) Specs

Identifiers: Early/Late 2008 - BTO/CTO - MacBookPro4,1 - A1261 - 2199

RAM Type: PC2-5300 DDR2 Min. RAM Speed: 667 MHz

Details: Supports 667 MHz PC2-5300 DDR2 SDRAM.

Standard RAM: 2 GB, 4 GB* Maximum RAM: 6 GB**

Details: *On October 14, 2008, Apple boosted the standard RAM to 4 GB.

**Apple officially supports a maximum of 4 GB of RAM but third-parties have been able to upgrade the system to 6 GB of RAM using one 2 GB and one 4 GB memory module.

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From my research, yes, you can install a second stick of RAM, as the system has 2 SO-DIMM slots.

This is DDR2 in early 2008, so a second DDR2 is possible, but you can not install anything besides DDR2 memory as will be capped out at your system BUS speeds, so if you install anything above 800, it will still operate at 800. but 800 speed RAM will work.

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