PowerMac G4 having problems with new RAM modules!

dear all,

I’ve recently got 2 512 MB Ram module from a British eBay dealer, to be used on 2 different but very similar PowerMac G4 AGP Graphichs 400 MHz machines.
I installed the first module in my father’s Mac, and it works fine, no problems of any sort. Then, a few days later, I installed the other module in my PowerMac, and immediately it started behaving very erratically: some programs didn’t open at all and others crashed with no warning, I tried to run Rember but it soon get stuck. I assumed the Ram module was faulty, emailed the dealer (who’s been very helpful) and then sent it back to get a replacement. The new module arrived yesterday, I installed it... and it was even worse: as some programs didn’t open as soon as the new module was installed, I rebooted the PowerMac but it hasn’t been able even to load the OS anymore, it just stopped at the blue screen forever, once came out a black screen and a Darwin login, but nothing else. As soon as I removed the Ram module the PowerMac started to work perfectly again.I'd assume again there's something wrong in the Ram module, but isn't it too much unlucky to get 2 faulty modules one after the other, or maybe the problem could somewhere else, in my PowerMac?!?
Unfortunately I can't test the new module in my father's machine, as we live 700 kms apart.
My hardware details are:
Power Mac G4
Model: PowerMac3,3
CPU: PowerPC G4 (2.9)
1 CPU
CPU Speed: 400 MHz
L2 Cache (per CPU): 1 MB
Memory: 896 MB
Bus speed: 100 MHz
Boot ROM Version: 4.2.8f1

thanks!

PowerMac G4, Mac OS X (10.4.11)

Posted on Sep 24, 2008 4:38 AM

Reply
17 replies

Sep 24, 2008 5:18 AM in response to Finrod

Here's something to be concerned about: "different but very similar PowerMac G4 AGP Graphichs 400 MHz machines." The different is acceptable if they are identical models. "Similar" may not be acceptable. Your analysis is capably and logically done and it shows the ram to be the likely problem. Did the vendor say that the memory matched the model that you describe in your post?

Sep 24, 2008 5:39 AM in response to motsteve

sorry if I'm not using terms like "similar" and "different" in the proper way but English isn't my first language!
My machine is a PowerPC G4 (2.9) while the other is a PowerPC G4 (2.8), else is the same (according to System Profiler).
Yes, vendor did say "the memory matched..", and also my "faulty" one looked exactly the same as the one that worked on my father's Mac.
I'll email the seller again... no idea if they'll change the module again though...

Sep 24, 2008 6:29 AM in response to motsteve

Hi-

Different latency isn't a problem with a Mac. The timing used is deterrmined by the SPD, and controlled by firmware parameters.
Moreover, Mac firmware is very specific regarding what RAM is acceptable.

Combinations of compatible DIMMs, in various sizes, is also no problem.

What is of importance, is quality, the density, and the coding on the EEPROM.
High density RAM will almost invaribly cause problems in a Mac.
Low density RAM is the desired memory for any Mac. Low density DIMMs typically have chips on both side of the board, as opposed to one side on high density constructed DIMMs.

Mac firmware has strict requirements of the RAM installed in a machine. If a DIMM manages to get by the POST, this is a good first step. But, low quality RAM and high density RAM may cause problems after the POST. Value RAM, and RAM not specifically stated to be Mac compatible is never a good buy, or wise to use.

BTW, the Sawtooth and the Gigabit Ethernet use PC100/PC133 DIMMs, Digital Audio and Quicksilvers all use PC133 DIMMs.

Gigabit Ethernet Memory Specifications

Sep 25, 2008 8:19 AM in response to Finrod

ok, I've now tried every possible combination... but with no success 😟
First, taking out one of the "old" 128 MB I realized it was one of the High density DIMMs (chips on one side only) Japamac was mentioning, in total 2 of the 128 modules were like this. However, taking out one or both of them, or even having only the "new" 512 MB module in, hasn't changed much, sometimes the OS booted, sometimes not but there were always some programs not opening/crashing and Rember got stuck with an error message. With just the "new" module the booting stopped at the blue screen (only blue, no apple splash screen in the centre).
With the new module plus one of the old 128 MB modules (the one with chips on both sides) Rember got stuck very soon, and the error message was:

Memtest version 4.2 (32-bit)
Copyright (C) 2004 Charles Cazabon
Copyright (C) 2004, 2005, 2006 Tony Scaminaci (Macintosh ports)
Licensed under the GNU General Public License version 2 only

Mac OS X 10.4.11 (8S165) running in multiuser mode
Memory Page Size: 4096
System has 1 PPC processor(s) with Altivec
Requested memory: 434MB (455589888 bytes)
Available memory: 434MB (455589888 bytes)
Allocated memory: 434MB (455589888 bytes) at local address 0x02008000
Attempting memory lock... locked successfully
Partitioning memory into 2 comparison buffers...
Buffer A: 217MB (227794944 bytes) starts at local address 0x02008000
Buffer B: 217MB (227794944 bytes) starts at local address 0x0f946000

Running 1 test sequence... (CTRL-C to quit)

Test sequence 1 of 1:

Running tests on full 434MB region...
Stuck Address : setting 1 of 16testing 1 of 16setting 2 of 16testing 2 of 16

I guess all this confirm the "new" module is faulty, I'll soon email the dealer 😟
Thanks to everybody for the help!

Sep 26, 2008 8:44 AM in response to Finrod

I know this is OT, but speaking of RAM expansion...

I once wanted to expand memory of my sister's Power Mac G4 Quicksilver M8359LL/A with PC133 SDRAM which I had recoverd from an old PC.

Specs: http://support.apple.com/kb/SP108

It had installed (when I got hands on it):
• 1x 128 MB
• 1x 256 MB
• 1x 256 MB* (not used)
Only 384 MB where shown in the System Profiler.

I had additionally available:
• 2x 256 MB
• 2x 512 MB
• 1x 128 MB

The problem is and was, that this Mac ignored individual DIMMs completely. Sadly it was one of the 512 MB DIMMs, while the other one worked.

The chips had close ID numbers from the same manufacturer. So it wasn't very logical to me why the Mac accepted the one but not the other.

The other strange thing was, that the one 256 MB DIMM, which had been installed already, was ignored too.

At least I got it to accept the folloging:
• 1x 128 MB
• 1x 256 MB
• 1x 512 MB

The enhancement was okay, but not as I had planned, as it could have been 1280 MB of RAM, instead I only got her 896 MB of RAM.

I switched banks, tried every DIMM individually, and so on. In the end this was the best it would get.

Why is it that these Power Macs are so picky when it comes to memory?

BTW, the Mac completely ignored these DIMMs. No instabilities. Mac OS X worked perfectly (as fas as I could see), and the system behaved as if this memory bank had been empty. (System Profiler didn't show the bank to be used.)

Of course, your situation is completely different. You experience instabilities while the memory is used by your system. I'd also say that the DIMM is broken.

Greetings,
Andreas.

Sep 28, 2008 8:56 PM in response to Finrod

I was upgrading the RAM in my sister's PM G4 400 AGP (Sawtooth), and discovered that (for no apparent reason), one of her ram slots was defective (the second from the center of the board). It would only see half of any module I put in, whether PC100 or PC133. The machine was bought new by her years ago, not ever damaged in any way, and was supposed to have two modules of 128 mb each installed - I found only one module installed when I opened it (I was the first person to do so other than the Apple store).

I have found this model, in general to be finicky, very quick to have problems with any changes to their configurations. It was very picky about what RAM I tried to install - it would reject a piece that the G4 Gigabit I was working on at the same time would have no problem with. And both machines use PC100 (PC133 only in certain configurations). I spent a long time arguing with it about a lot of upgrade possibilities (the mac not my sister), but finally had to accept that that was just the way it was. I've never had so many silly problems with a Mac since I tried to deal with a first generation beige G3 (which the Sawtooth is also in it's own genre - first generation). I know it's a machine, but yeegaads, it was so inflexible.

I don't know if this is of any help, but good luck.

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PowerMac G4 having problems with new RAM modules!

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