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SDRAM, CAS Latency for the

Q: Concerning the timing parameters for PC133 SDRAM DIMMs, what CL (CAS Latencies) are the newest G4s firmware wired for?

A: The DIMMs shipped with the PowerMac G4 CPUs are typically CL 3.

However, the UNI-N memory controller in the current family of PowerMac G4 CPUs (towers) can accept either CL 2 or CL 3 timing parameters. Other information on UNI-N and RAM Expansion for the PowerMac G4 CPUs can be found in the current developer note at the following URL.

http://developer.apple.com/documentation/hardware/Developer_Notes/Macintosh_CPUs-G4/PowerMacG4/0Preface/index.html

In addition, RAM modules for use in Macintosh computers must support the correct timing modes and their Serial Presence Detect feature must be programmed accordingly, as called out in the JEDEC specification.

[Sep 13 2001]

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