from time to time there are threads here on issues around installing RAM. Here is another one.

I had ram lying around everywhere, all unidentified, and I knew one of them was a 512 stick, so I tried them all out in a G4 400 (with 1.25 already installed). Identified the 512 stick and so I have 1.75gb ram installed, with everything seeming to work fine. Next I install iWork 05, while I am having a bite to eat away from the 'puter. Come back and it's dead, nothing.

No probs, I restart, it chimes, but nothing. No probs, I insert OSX, restart while pressing 'c', still nothing. Mounting concern now, how could installing software distroy my operating system? Stop, think, (q) what is new? (a) the ram. So I take the 'puter back to a much simpler configuration (turn off attached drives/devices, remove 3 ram sticks) and reboot. It works normally.

The moral? Probably 2 or 3. Stay in front of the 'puter when installing, so you can see what is happening. If something untoward happens, don't panic, think what has changed and reset to original configuration. Flaky RAM is often the answer, as many here have noted.

sao

Edit: to clarify. this is an AGP G4 400 running 2x 160gb ata hdds internally, the standard 16mb video card, 1.75mb ram, 10.4.8, dvd rom and a 250gb usb2 external hdd (connected through a pci card). It has a scsi pci card, but its not being used.

The moral of the story should be don't try to install 1.75GB RAM into a machine that can only address 1.5GB

Ha. Right!

From low end mac...

RAM: 64/128/256 MB standard on 400/450/500 MHz models, expandable to 1.5 GB using PC100 SDRAM (3.3V, unbuffered, 64-bit, 168-pin, 100 MHz) in 4 DIMM slots

Suddenly my 1.25 doesn't seem so bad anymore...

Thanks for sharing that with us. I'm about to buy some more RAM and I'm a bit nervous about it all actually.

I reseated and re-ordered the ram and its happily addressing 1.75. (some of its sd100, some sd133 and it seems particular about the order). I have seen an emac recognising 2gb (supposed 1gb limit). soon as i can find another 512, will see if the g4 will address 2gb, my gues is that it will.

Isuru, dont worry, this is the first itme I have ever had an issue with ram, therre are bad ram sticks, but they are rare. Really its a tale about not panicing, usually the answer is pretty simple.

sao

I learned something new then (it would appear I was right and wrong in varying measures). It does quite specifically depend on the G4 400 in question. PCI Graphics 1GB (max' and will not support 512MB DIMMS at all: 64MB to 256MB DIMMS only), AGP graphics 1.5/2GB, Gigabit ethernet 1.5/2GB (the second numbers refer to OSX support: 64MB to 512MB DIMMS can be used in any configuration). It does go to show that we (I) should always qualify statements. PCI graphics models owners would be annoyed by the failure of advice in the initial post while the AGP graphics and Gigabit ethernet owners would be pleased by confirmation of a poorly advertised feature. Very few articles (non Apple) document this clearly, if at all, and searching Apple documents can be frustrating at times.

From Apple, specifically note 6, from the link, as per quote below:

Interestingly, in a seemingly regressive step, Apple then dispensed with the 4th RAM slot for later faster models e.g. the Digital Audio and Quicksilver. The PCI graphics had 4 PCI slots and 4 RAM slots, the AGP graphics and Gigabit ethernet lost a PCI slot (3 slots) to make room for the AGP slot and kept 4 RAM slots. The later Digital Audio and Quicksilver models dropped a RAM slot to make way for an extra PCI slot; making only 3 RAM slots, 4 PCI slots and an AGP slot. Possibly by this stage RAM was physically cheaper making the use of 512MB modules an economically viable option and Apple opted for the expansion options that 4PCI slots would offer.

cheers