MDD G4 RAM issues

If you are using RAM that is slower than the computer specs you could get problems that only show up when all the modules are installed. The extra modules put more load on the data and signal lines, and slow everything down slightly. If it barely worked with three modules, the extra module would make it fail. Heat also has an effect, so the failure might not be immediate.

Apple has a nice tech note that the "PC2600" that shows in 10.3.0 and later's System Profile is just "cosmetic" and misreporting the PC2700 (AHT reports it correctly though).

It is either essential or helpful to totally reset nvram when changing RAM configuration, not just zap PRAM even. Use Open Firmware.

"Apple Reseller" can vary far and wide in what you get.
Stick to Crucial, RAMjet, Samsung, is my advice.
You can use PC3200 DDR400 as long as it is for G4 or G5 and for Macs and has the correct voltage and timing etc.
http://www.crucial.com/mac

As soon as you have the memory in, hold down command option o f to get to Open Firmware,

reset-nvram
set-defaults
reset-all

And when you can, run Rember or Memtest (the later can be run from the command line and from Single User Mode).

Substandard memory. Read the BAD RAM report @
http://www.macintouch.com

Frobro which RAM finally worked 2700?

I recently purchased four 512mb DDR 3200 dimms for a MDD from Cruicial. I can only get the machine to work with 2 of the 512's installed in the first two slots closest to the CPU. I was able to place the two 256 2700 dimms that came with the machine in slots three and four without any problem getting the total to 1.5Gigs.

I have read thru some similar posts with the same problems. Can anyone confirm that it is best to just go with 2700 dimms if you want to run with 2Gigs of RAM.

I have already tried using Open Firmware to reset nvram etc. The machine will not start up when all four slots are filled with 3200 dimms. Take out 2 and it works fine.

MDD G4 Dual 1.25Ghz

To append my earlier post the 512 3200 dimms Crucial sent me have all the modules on one side of the board.

Does anyone have 4 512 PC3200 Crucial dimms running in a Dual 1.25 MDD machine?

It is the last Dual Boot machine.

Boot ROM Version: 4.4.8f2

MDD G4 Dual 1.25Ghz Mac OS X (10.4.7)

Thanks Frobro.

Where the ones that would not work PC3200? You mentioned 2600 but there seeemed to be some confusion on whether this was just the false reading by System Profiler or did your dimms physically have 2600 written on them.

I am exchanging the 3200 for 2700. I hope this will end the matter with it not being the RAM slots that are bad.

All the DDR DDR2 RAM seems like a mess. The next generation is going to be FB-DIMMs. It is a standard built by Intel. With 64bit CPU's FB-DIMMs will scale up to 192gigs of RAM for the system to work within.

In the mean time for me 2gigs would be great.

MDD G4 Dual 1.25Ghz Mac OS X (10.4.7)

The 512mb PC2700 dimms arrived.

Still a no go. The machine at least started up with all of them installed. It only took a few minutes at most until the system froze. It seems to run with 2 of the 512s in the first two slots next to the CPU and the 2 256 dimms in slots 3 and 4.

The Dimms are good because I tried them in an identical MDD without any problems.

Did anyone have this problem fixed thru AppleCare? If so was the problem fixed with a motherboard replacement.

Well a funny thing happened on my way to the forum.

The start up chime on this machine was really loud. Abnormally loud. I was able to get it to start with a normal chime by lowering the volume in Mac OS 9. It did not last past a shut down and restart.

I changed the ROM battery. Chime works normal now.

Installed 2GB RAM machine starts up without issue. It has been running several hours without any freeze ups. I did do an open firmware nvram reset to get it going.

Hopefully this was the problem.

MDD G4 Dual 1.25Ghz Mac OS X (10.4.7) 2048 RAM

To finish up my conversation with myself.

My MDD indeed has two bad RAM slots. Slots 3 and 4 are just to problematic. The machine will only run stable with only 1GB of RAM installed.

These are nice machines but running 1GB of RAM is a bummer.

MDD G4 Dual 1.25Ghz Mac OS X (10.4.7)

Hi Hatter,

I'm going to hop in here as I"m about to add 1 GB of RAM to my G4.

Aside from the instructions to reset the nvram, i just want to be clear that i also need to reset the Pram too? Would I do that before or after the nvram?

Thanks. I'm a bit nervous b/c i have projects on the system (some of which are backed up) and I don't need/want any issues 🙂

Cheers,
Keebler