A MDD, new RAM and issues

[Bolkonskij]

hey everyone,

finally got around spending the 15 bucks to get my MDD 4 x 512 MB RAM modules. Seller listed them on ebay as PC2700U modules. When I put them into the Mac everything worked fine, but my apps keep crashing a lot and it shows strange behavior like e.g. suddenly unstuffing files won't work properly (those files used to unstuff fine - and do so for everyone else).

Thinking that at least one module might be bad I checked the RAM with TechTool Deluxe 4.x. It detected no problems, but listed the modules as "PC2600U-25330" modules. I booted back into Tiger to see what system profiler says and I get the same: PC2600U-25330. (again - four identical 512MB modules)

I know that the MDDs can be picky about RAM - could that be the troublemaker? Anyone ran into similiar issues on their MDD before?

[GaryN]

There's really no such thing as PC2600 RAM………… EXCEPT for the fact that some very early PC2700 was labeled/mis-labeled 2600 for a short time.

That means your RAM is…… OLD. THAT begs the question: Where did it come from? Most likely it was pulled from a parted-out old computer.
That alone makes it suspicious.

Note that there are RAM issues that TechTool will not detect. Why? Because any software-based tool can only test the RAM that is available.
The RAM used by the app itself and that used by any other apps AND the operating system (big one!) cannot be tested.

I used to run a command-line tool called "memtest" that would sequentially write and read from each and every block/bit in each chip.
On the plus side, it uses virtually NO memory and does not require the OS to be loaded either, so it tests 99%+ of the RAM.
On the down side, it takes literally all night to run.

I don't think it's in MacGarden and I'll have to dig for it. That said:
I think you have made a penny-wise / pound-foolish choice. You can buy brand-new RAM almost anywhere for around 6 or 7 bucks per 512mb module.
So, the $10 you saved buying mysteryRAM on fleabay would probably have been better spent at Starbucks.

I'm just sayin'……

[IIO]

i never understood this numbering scheme but 2600U-25330 is 2700U with 333 MHz and that it what apple originally put into the quicksilvers.

maybe the 167 bussed G4 need something else?

MDDs should accept most faster units, too, like 4200.

[FBz]

Und now zee obligatory commentary on “housekeeping”.
(Nope not gunna get into the PC2600 vs. PC2700 debate.)

Dust & oxidation of slots / contacts (und RAM) do occur over time.
Especially if both are elderly and have been sittin’ round unused.

Intermittent or random poor connections (especially when under demand)
can cause a bit of the mysterious behaviors. Clean, clean and then retry.

*I’ve several sticks of the 2600U-25330 here that have never been used
…mainly because I didn’t know what they were originally intended for.
(Maybe N.G. for MDD but Quicksilvers might love them?)

And yes, I’d be interested in “memtest” too.
(As if it’s not already hiding here in my home archives.)
https://osxdaily.com/2011/05/03/memtest-mac-ram-test/

[GaryN]

i never understood this numbering scheme but 2600U-25330 is 2700U with 333 MHz and that it what apple originally put into the quicksilvers.

As usual…

Quicksilver:   PC-133 3.3v, unbuffered, 8-byte, non-parity 168-pin SDRAM

MDD:            PC-2700 (dual 1+) 2.5v, unbuffered, 8-byte, nonparity 184-pin DDR SDRAM

[FBz]

Well, Quicksilver or MDD…
some machine here is getting some new (old) RAM.

Snippet:
“ASP is wrongly reporting "PC2600"
(Apple has a tech note even - began with 10.3.0,
though AHT reports RAM correctly).”

[GorfTheChosen]

I just found two bad modules here:

1. 128MB 5v SDRAM DIMM in the Power Mac 9600

2. 512MB PC133 DIMM in the Power Mac G4 Dual 800 "Quicksilver"

Was hoping that No. 2 would be the cause of the kernal panics I've been getting on booting from "power off" state in the Quicksilver but it's still doing it ... 

Used Granger's "TestMem" utility (attached below) to test them - which is a Mac OS 9 (and below) utility:

[IIO]

Quicksilver:   PC-133 3.3v, unbuffered, 8-byte, non-parity 168-pin SDRAM

MDD:            PC-2700 (dual 1+) 2.5v, unbuffered, 8-byte, nonparity 184-pin DDR SDRAM

i remember reading somewhere that a lot of confusion once was created because of a typo in an apple powermac manual.

however, not ideal when someone sells you something which says "number 7" but in fact its number 5a. that is far more disturbing than ones own error.

[IIO]

this one is fine

https://www.ebay.com/itm/Crucial-Technology-CT12864Z335-1GB-184-Pin-PC2700-333Mhz-DIMM-DDR-RAM-Memory/161516880202?epid=92848577&hash=item259b28014a:g:BIEAAOSwg3FUgxsq

just 500, of course, not 1000.

but as you can see there is no real reason to buy oscure second hand / hong kong variants here.

watch out, not every app is able to detect errors like your unarchiver did. so you might destroy files if you save something opened with faulty RAM.