[milhaus]

From MacFixit:
Basic explanation of the Problem: Apple, while previously recommending to those in their Developer Program to ship the faster 2-2-2 coded memory (i.e., Apple TIL article 58182), has now changed recommended CAS settings on the memory to 3. Essentially, Apple decided to slow the systems down somewhat for stability and reliability. Any RAM that is not coded to the latest JEDEC Standard EPROM and is hard-set to run at CAS-2 will be rejected as "out of spec" after the firmware upgrade in the G4. This is NOT an indication of product quality or meeting Apple/Intel specifications.

Apple Test Lab personnel have indicated that they have essentially given up on the problem, leaving it to the memory manufacturers to solve the problem. The firmware upgrade is a one way ticket and cannot be reversed.

Does this make sense, and now, is it Apple's fault? (doesn't seem to be about quality, but the reverse)

[vega24]

I think the above statement is correct. I updated the firmware on my iBook before I purchased a memory upgrade and everything was fine but the only memory I had installed was the factory 64MB that's soldered in. Last week I ordered a 128MB stick and guess what, it was unrecognized. I found a patch called DIMM First Aid and it said the memory was set at CAS 2 and that it could reprogram the EPROM to run at CAS 3. I called Mushkin first and told them what had happened and they said no problem we'll send a new stick of memory out to you overnight and that they would reprogram it to run at CAS 2. Now, I ran DIMM First Aid and let it reprogram the EPROM to let the memory run at CAS 3 and 10ns. BAMM BOOM, I restarted my computer and well, the computer now recognizes the new memory but only as 64MB instead of 128MB. The next day the replacement memory came and I installed it but the computer wouldn't boot up with it installed. It would make three pulse tones and then the sleep light would flash one long and three short flashes. My guess is it won't work because it's programmed to run at CAS 2 only.

To make a long story short, the memory that was hard set to run at CAS 2 would not work at all but the memory that I reprogramed to run at CAS 3 and 10ns works fine now except that it's recognized as 64MB instead of 128MB. Hope this helps.

[AirSluf]

MacFixIt doesn't know what it is saying here, while Apple may have changed it's recommendation, 2-2-2 memory still works post update. My Gig says so.


There was a lot of coverage about the firmware update in www.xlr8yourmac.com and someone worked up a shareware DIMM reader that found nearly every unrecognized Dimm had errors in it's on chip E-Prom and he also was providing customized Dimm updaters that made the Dimm work again.

Not a case of changing specs to change performance, but finally enforcing the published spec in hardware. Lot's of RAM, both quality and cheap did not have great attention to detail paid when it's on chip ID was burned, even though QA made sure the memory itself worked as advertised. The Mac community is lucky this chap had the time, knowledge and motivation to find the problem and solution all in the first coulpe days.