G4 MDD Powermac RAM upgrade

The eBay RAM you mentioned should work fine. As you have the MDD with the 166 MHz front side bus, you need at least PC2700 RAM - anything greater will also work fine.

The MDD isn't terribly picky about matched pairs, I've tried out all sorts of junk box RAM in mine and I've never had a problem - apart from using RAM that's too slow. You can also use 2x 1GB sticks to get to the full 2GB, but unfortunately the memory controller cannot see any more than 2GB.

The MDD isn't terribly picky about matched pairs, I've tried out all sorts of junk box RAM in mine and I've never had a problem - apart from using RAM that's too slow. You can also use 2x 1GB sticks to get to the full 2GB, but unfortunately the memory controller cannot see any more than 2GB.

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I'd like to reach out to harrymatic for some help understanding your statement quoted above. I have seen the 1GB PC3200 DDR RAM at OWC and thought, gee, I could bump the RAM in my G4 MDD 2003 to 4GB. I've seen the 2GB limit elsewhere but don't really understand why. Could you enlighten me more about the memory controller? Is it replaceable/upgradeable to recognize more RAM? I've been searching far and wide to try to understand this, with no success, and then you mentioned the "memory controller", and gave me some hope.

Thanks in advance for your time.

Best regards,

Mark Harrison

The memory controller is not replaceable or changeable. While the machine can physically contain 4GB of memory, it can only ever use and see 2GB.

fymbscu said:

I'd like to reach out to harrymatic for some help understanding your statement quoted above. I have seen the 1GB PC3200 DDR RAM at OWC and thought, gee, I could bump the RAM in my G4 MDD 2003 to 4GB. I've seen the 2GB limit elsewhere but don't really understand why. Could you enlighten me more about the memory controller? Is it replaceable/upgradeable to recognize more RAM? I've been searching far and wide to try to understand this, with no success, and then you mentioned the "memory controller", and gave me some hope.

Thanks in advance for your time.

Best regards,

Mark Harrison

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I don't know the details of "how" or "why" but do know that the memory controller in the MDD just doesn't have the ability to "talk" to more than 2gb of memory.

The Powerbook G4s are the same way. The last generation(DLSD) Powerbooks use DDR-2 RAM and it's conceivably possible to stuff 4gb of RAM into one, but nothing over 2gb will be read. I have one now that's running off a single 2gb stick(I was out of 1gbs, and didn't want to buy more RAM).

Not even all MDDs will read 1gb sticks, and I don't know of any reliable way to tell without experimenting. I've had MDDs that handled them fine(my dual 867 has a pair of 1gb PC-2100s in it now) while others may read the 1gb sticks at half capacity or not see them at all. I mostly just stick to putting 512mb and smaller in MDDs to save headaches-I only tried the PC-2100s in the dual 867 because I got tired of grabbing them out of my DDR drawer by mistake(my dual 867 and single 1ghz FW800 are the only computers I have that use PC-2100).

I'll go so far as to say that I'm not aware of any G4 based computer that can take more than 2gb. The G4 towers max out at anywhere from 1gb to 2gb(1gb for the Yikes!, 1.5gb for the Cube, Digital Audio, and Quicksilver, 2gb for the Sawtooth, GigE, and MDDs). Powerbooks will take between 1 and 2gb(1gb for TiBooks, 2gb for 15" and 17" AlBooks, and the 12" can take 1gb+whatever is soldered to the board).

Thanks for the replies, guys. I'll probably stick with the 512MB sticks.

Had another thought, though. Am in the process of adding SATA and USB 2.0 PCI cards. (Already have a SCSI card installed also.) Would using only 2x1GB sticks provide any cooling/energy advantages, since it would allow two open RAM slots?

Best regards,

Mark Harrison