Computer Memory (RAM)

This page is obsolete
See Mac Configuration for more current data

Why upgrade memory:

The main reason is better performance.
Some programs require more memory.
Adobe Creative Suite (Photoshop, ...)
Gaming, Video Editing, 
Virtual Machines to run MS Wndows (e.g. parallels and VMware Fusion)
Some Considerations:

Performance tests at OWC


Specs. e.g. For 2.5GHz MacBook
4G (2x2GB) from Other World Computing (OWC) (macsales.com) $50
# Technology: DDR3 SDRAM  # Density: 2GB (2048MB)
# RoHS: Yes               # Comp. Count: 16
# Depth: 256Mb            # Width: x64
# Pin Count: 204-pin      # Op. Temp.: 0C to +85C
# Data Rate: DDR3-1066    # Speed: PC3-8500
# CL: CL = 7              # Cycle Time: 1.875ns
# Voltage: 1.5V           # Comp. Config: 128 Meg x 8
# ECC: Non ECC            # Module Ranks: Dual Rank
# Register: Non Parity    # Low Noise 8-Layer PCB

4GB kit (2GBx2),  from Crucial.com $48
# Module Size: 4GB kit (2GBx2)
# Package: 204-pin SODIMM
# Feature: DDR3 PC3-8500
# Specs: DDR3 PC3-8500 : CL=7 : Unbuffered : NON-ECC : DDR3-1066 : 1.5V : 256Meg x 64 :

What it means:
Data Rate - DDR-1066 - Double Data Rate @ 533MHz *2 The Front Side Bus (FSB) connects the Central Processor Unit (CPU) to a Memory Controller HUB (MCH). THe memory bus is typically slower than the CPU. NON-ECC/Non-parity Ñ Most desktop and laptop computers take NON-ECC or Non-parity memory.

ECC/Parity Ñ ECC or parity modules look for errors in data and are most often found in servers and other mission-critical applications used by large networks and businesses.

Unbuffered Ñ Most PCs and workstations use unbuffered memory which is faster than registered memory.

Registered/Buffered Ñ Registered or buffered modules delay all information transferred to the module by one clock cycle. This type of memory is primarily used in servers.

Fully buffered Ñ Designed for next-generation servers, features an advanced memory buffer.

CL Ñ CAS (column address strobe) latency, which is the number of clock cycles it takes before data starts to flow after a command is received. Lower CL is faster. Modules with different CL can be mixed on a system, but the system will only run at the highest (slowest) CL.

Component configuration Ñ (For example: 64Meg x 64) Indicates the size of the memory chip components on the module.

Voltage Ñ For example 2.6V. Indicates the power used by the module. The lower the better.

DDR SDRAM - Double data rate synchronous dynamic random access memory

How to Install:
Most sellers have online videos on now to install memory.

Notes:
Some versions of Macs my require a boot ROM upgrade to support 8GB

Sellers:
RAM Memory Upgrade: Dell, Mac, Apple, HP, Compaq. USB drives, SSD at Crucial.com

Links:
Memory and Drives for Snow Leopard Mac OS X 10.6
Installing laptop memory
Computer Performance - Maximum Performance Computing Defined

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last updated 3 Nov 2006