[chasg]

Hi All,

I've got two 256Mb PC133 DIMMs from a G4/500 that's defunct, and I want to know if I can put them into my Blue and White G3 (which is my server).

Well, it's confession time: I actually did put them in already, but they are showing up as 128Mb modules (I've taken them out)

Why would they be showing up as 128Mb DIMMs instead of the 256Mb modules I know them to be? Can I put them back? (hey, an extra 256Mb of RAM for my server can't hurt, unless it can...)

TIA for any help,

Chas

[made an edit to correct grammar]

[dreilly1]

Putting the 133 modules into a B&W is no problem; they'll just run at 100 MHz.

The ram problem you're seeing is because of the actual RAM chips used on your RAM sticks. The B&W G3 could only use 256MB RAM sticks at full capacity when a particular size of chip was used in a particular configuration (I don't remember the details, so I'm being intentionally vague). When you put your 256 MB sticks in, since it's a different configuration you'll end up only seeing half the RAM.

There's nothing wrong with this setup: your B&W will function just fine like this, and it won't hurt your RAM at all. I did this for a while with my old venerable Smurfy Mac before trading it earlier this year...

[msuper69]

"When using 256MB DIMMs, use 128Mbit-device technology, not 64Mbit or 256Mbit."

This is an excerpt from the official Apple B&W G3 FAQ

Is this possibly the problem?

[dreilly1]

Originally posted by msuper69:
"When using 256MB DIMMs, use 128Mbit-device technology, not 64Mbit or 256Mbit."

This is an excerpt from the official Apple B&W G3 FAQ

Is this possibly the problem?

Yup. I think I remember that my 256MB Ram only had eight chips on it, and 256Mbit * 8 = 256 MBytes.
The B&W must be looking for a 256 MB stick with 16 chips, so 128Mbit * 16 = 256 MBytes.

Plugging a 256Mbit stick into the B&W will result in the unit only being able to physically address half the ram. But if the system is designed well, the other half won't be damaged, it would just be inaccesable.

[chasg]

thanks for that info guys (and the peace of mind).

I'm at a different computer now, but I do believe that all of the modules in question had more than 8 chips (there were chips on both sides), so I'd be willing to be that they are 16 chip modules.

Funnily enough, as I was swapping RAM around to better understand this problem, the machine had a kernel panic. I finally managed to partially isolate the problem: it happened when a particular 128Mb PC100 module was installed at the same time as the one PC100 256Mb module I have. Take one or the other out, and no panic, but having both in at the same time was a problem.

I think the B&W is mad at me for leaving it on the floor the last few years...

Thanks again for clearing up my first problem!

Chas

[dreilly1]

Originally posted by chasg:
Funnily enough, as I was swapping RAM around to better understand this problem, the machine had a kernel panic. I finally managed to partially isolate the problem: it happened when a particular 128Mb PC100 module was installed at the same time as the one PC100 256Mb module I have. Take one or the other out, and no panic, but having both in at the same time was a problem.

Sometimes the position also matters. Did you try swapping them?

[chasg]

I've tried a few combos (I didn't document them, was just doing a bit of testing).

I'll try all the combos and see if I can get them all running, thanks for the suggestion!

[Eriamjh]

It's the Ram density. 128MB is all your gonna get. So either live with it or put them in a machine that can use all 256MB.

[tooki]

Or find someone willing to trade them for the proper-density 256MB PC100 modules.

tooki

[chasg]

last two suggestions are good ones, thanks (I've decided to split the modules in question between the B&W and the G4/500 I'm going to sell)

Thanks everyone for all of the info and advice,

Chas