PC-133 RAM Limited by Firmware Update?

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Date: Sunday, July 29th, 2001, 15:18
Category: Archive

Go2Mac reader Eddie writes to us about a recent discovery with PC-133 RAM:


I’ve come across something a little odd about Apple’s firmware updater 4.1.7 and 4.1.8. It claims to enhance performance and stability but it only does one of these, it increases stability and decreases performance.


Go2Mac reader Eddie writes to us about a recent discovery with PC-133 RAM:


I’ve come across something a little odd about Apple’s firmware updater 4.1.7 and 4.1.8. It claims to enhance performance and stability but it only does one of these, it increases stability and decreases performance.

All G4 AGP, PowerBook G4 and Blue Dalmatian iMac models and up all ship with a 100 MHz system bus. I have always used PC133 RAM into these machines as Apple says you should use 8 NS 125 MHz RAM. The only RAM that meets this specification is PC-133, yet Apple says you must use PC-100, confusing isn’t it?.

To my surprise, I installed a piece of PC-133 RAM into all of the above computers before installing the firmware update and showed up as PC-133 CL3. I was amazed at this and thought they only read these chips at a maximum of PC-100 2-2-2. I was even more surprised when I installed the firmware update it showed up as PC-100 2-2-2, when before it showed up as PC-133 CL3.

I was curious to see if there was any performance gain between the non-updated machine and the machine with updated firmware since both are using PC-133 RAM. One, as you will expect, runs at 100 MHz the other 133 MHz. I ran a series of Photoshop tests as well as benchmarks and the non-updated machine smoked the updated machine by 40% in terms of time and memory throughput.

I thought to myself this is incredible. Why would Apple give us a firmware update that would decrease system performance when saying it would increase it? Also, why hasn’t Apple said that we could use PC-133 RAM in these machines? I called Apple technical support and explained what I had found and they couldn’t explain it.

What has your experience been with PC-133 RAM and firmware update 4.1.7 and 4.1.8? If you know more about this issue, drop us a line.

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