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[aBc]

Think I’ve another 2003 MDD J20 RAM slot problem here.

This 1.25 GHz SP MDD, loaded with four 512 MB RAM sticks would only occasionally fully boot from a cold start before freezing and then NOT completely restart (or fully boot) before immediately freezing. And by now don’t we all know to remove all but one stick of RAM and then test and retest with each stick of RAM alone, in order to possibly determine if there’s a bad stick. Right?

Well how many of us (like myself) usually test in this manner, leaving (or placing) each individual stick in the MDD’s J20 RAM slot? (In my case, thinking that the J20 slot is the first memory slot addressed by the machine.) So, when testing this machine in this manner… none of the four sticks individually would allow the MDD to fully boot before freezing. Was all of the RAM faulty?

NO.

Placing any of the four sticks individually, in other than the J20 slot… would then allow the MDD to fully boot. Seems like this is more than just a bit familiar to me.

See: https://macos9lives.com/smforum/index.php?topic=6285.msg47109#msg47109

Now I do wonder just how many MDDs might have somehow ended up e-wasted or otherwise possibly abandoned… simply because of this expanded  J20 RAM slot condition?

             

Sure, I could run just three, 512 MB sticks in the J21, J22 and J23 slots for a total of 1.5 GB... or try a 1 GB stick + two 512 MB sticks for 2 GB — and leave the J20 slot empty. (Or so I have been told.) Or I could even swap out the mobo with another mobo, without this J20 slot problem? But still, I wonder what is the root cause of this problem?

RAM placed in the J20 slot here seems to be a bit more loose in the slot and as mentioned in the link above… but this was remedied before with a slightly “thicker” stick of RAM that seems to now have solved that problem since 2022. (0.003 inch thicker!) And as much as I swap RAM in and out of machines I first thought that the “loose” J20 slot was a result of possible “wear”. But now I wonder if it might be a consequence of its location near the GPU and all of that heat emanating from that GPU heatsink over time? And perhaps especially… if the GPU has also been powering an Apple ADC monitor for most of its life?

GPU pictured above has a fan, whereas this MDD and the previous one here did not. Lot of cumulative running heat cycles to consider since 2003. And I found no weakened or faulty J20 solder joints back in 2022 with the other machine. So I assume that some heat related expansion of this slot (over time) might actually be the culprit?

I may swap out the mobo and retest all over again. And if that works, Mardeec might be getting this MDD back to use — or to possibly even sell on good ol’ flea-bay. Can anyone resist having at least one of these MDDs, especially one like this in near perfect condition? I think Mardeec’s original $1.00 offer to Forum members for this machine is no longer in effect.

https://macos9lives.com/smforum/index.php?topic=7630.msg59104#msg59104

Anyone running a 1 GB RAM stick in an MDD (or Quicksilver)? Do speak up please.
UPDATE:
Found a loose, thicker (0.053 inch) 256 MB stick of RAM here last night and inserted that into the J20 slot, which brought the RAM total up to 1.75 GB. It then booted and ran flawlessly, playing music CDs for 3 hours without fail. So… swap mobos or just accept the 1.75 GB as good enough (for now)?

[chrisNova777]

according to the numbering of the slots.. it would seem that the ram is intended to be installed in matched pairs, the two outer slots are one channel and the two inner slots are another channel, if its dual channel memory thats how the G5 memory has to be populated... i didnt know the mdd was the same way but according to that number scheme that would be what that means to me logically from lookin at it

[aBc]

Thanks Chris, I hadn’t considered that. It does seem to be working stable at present (even with all of the mis-matched RAM and the 256 MB stick now added in the J20 slot).

Seems that info about this is currently sparse and even posts in the “Apple Community” vary on the use of 1 GB sticks in the MDD. AND Google’s AI results seem to offer a bit of conflicting / confusing info about 1 GB RAM.

First, from the Apple Community (and Japamac’s response).
https://discussions.apple.com/thread/1307763?sortBy=rank (12/26/2007) 

Then… three different current screenshots from Google’s AI - also attached below.

*I really believe that the J20 slot has expanded over time.

[DieHard]

according to the numbering of the slots.. it would seem that the ram is intended to be installed in matched pairs, the two outer slots are one channel and the two inner slots are another channel, if its dual channel memory thats how the G5 memory has to be populated... i didnt know the mdd was the same way but according to that number scheme that would be what that means to me logically from lookin at it

No totally different, not necessary to install in pairs, however AFAIR the MDD supported Memory Interleaving, so in theory, you should get better performance with matching pairs; neither configuration should introduce errors; also, it's a good idea to hit each slot with a crazy amount on canned electronic cleaner and also inspect tiny RAM claws to find any stuck any not sitting at the optimal height

[refinery]

MDDs will run fine with two 1gb sticks. I have been doing this for years to allow for a quiet heatsink on my Radeon 9800

[aBc]

Hey @refinery, thanks!

Which two RAM slots are your 1 GB sticks in?
Do we consider the J20 slot as number one?



OR… is J21 considered Slot 1?
[In which case, perhaps J23 is considered to be the number 3 slot.]

         



Again, it’s the J20 slot which seems to be the problem w/ this machine.
Mardeec had thoroughly cleaned it - and I did it again, twice afterwards.


Und NOTE:
For all that previously used the low-cost, CRC brand Electronic Cleaner,
that cost has risen from less than (or near) $5.00 — now to $8.48  USD.
*And Walmart now only offers it via online order.

[refinery]

I use J21 and J22, the two closest to the CPU heatsink. It provided the most clearance for the GPU heatsink. I actually had to remove the locking clips on J20 for it to fit right.
I know I probably sacrificed a little performance by not using interleaving, but having a quiet system was more important to me.

[aBc]

Thought there might be a better approach to test and compare… but QuickBench 2.0 did reveal a very major difference between two interleaved 1GB RAM modules and then same modules not interleaved. Such a difference that I find it very difficult to believe, even after testing twice. So I have ordered another matched pair of 1GB RAM to test all over again.

The first column is from Mardeec’s 1.25 GHz DP MDD (with the questionable J20 RAM slot). I found a “thicker” 256 MB stick of RAM that works in that slot, so all four slots were filled. Then (same machine with same SSD) was tested with and without interleaving. I did expect results to all be much closer. But if these results stand after another test… well there is a definte advantage to interleaving.



If the image above is difficult to see clearly you might try double-clicking the attachment itself, below. OR change your Forum theme to “Blu” temporarily. (You can change it back afterwards.) *Yes, if you’re using the Forum or Board Default theme OR the Mac OS 9 Lives 3.0 theme, it might be best to just drag the image file to your desktop and open it there.

The big blue numbers represent average of each individual test panel. Red numbers at the bottom are the overall averages of all three panels, of each individual test / configuration, in order to provide an overall one-number “rating”.

[*The first 1 KByte Transfer Size results were omitted, as those results often are noted in KB/sec.]

AND if testing with the different, newly ordered 1GB modules doesn’t provide much difference… there won’t be another test update from me on this topic. (Did I just hear a collective sigh?)

But really, a nearly one-third drop in overall performance?

[refinery]

That kind of doesn't make sense because 3x 512 + 1x 256 isn't an interleaved configuration yet the results are similar to the 1gb interleaved.
I will have some time over the next few days to test mine and I'll report back

[aBc]

That kind of doesn't make sense because 3x 512 + 1x 256 isn't an interleaved configuration yet the results are similar to the 1gb interleaved.
I will have some time over the next few days to test mine and I'll report back

Thanks refinery. I agree that it doesn't seem to make sense. Maybe it is because OS 9 only utilizes 1.5GB and as long as that’s available [especially when testing with QuickBench Classic (2.0) which IS OS 9 based] interleaving might not matter. Yet when one uses only the (2) 1GB sticks, interleaving can improve performance? Perhaps just as matched pairs of (4) 512MB can do?

The three 512MB sticks that I used (in J21, J22 and J23) were all matched and the same. The 256 of course, wasn't. And of course, depending upon just how your machine is configured or loaded up. This machine here is a bare bones sort of machine with a 128 GB SSD and no other internal cards, other than the GPU.

Before you get way out here in-the-weeds with me… if you’ve room to move the 1GB RAM in J22 to J23, you might then test with QuickBench Classic [2.0]. After moving the RAM to J23, boot up and zap the PRAM and then rebuild the desktop prior to running QuickBench. Otherwise you may only see results like what you might get from slots J21 & J22.

I just tested 2 different, new pairs of 1GB RAM in J21 and J23 and at first they all tested like the previous, non-interleaved results. I zapped the PRAM and rebuilt the desktop and retested after each pair change of RAM. QuickBench results then matched the previous interleaved results.

*QuickBench 4.0 runs only under OS X and thus, likely tests the full 2GB of RAM under OS X?


Also… just ran Apple Service Diagnostic (ASD v2.1.5 for the 2003 MDD) with one pair of the new 1GB RAM sticks installed and it PASSED every test. Like a big dummy... I didn’t select specific tests and it took over 35 minutes to complete ALL of its tests. I don’t like that I can’t simply screenshot the results & text - or all of the tests that ASD runs — but here’s a somewhat “reconstructed” iPhone image after only 15 minutes of runtime (it says 15 minutes, anyway).



Really like ASD v2.1.5 and wonder how it might test out with the original pair of 1GB RAM. (But not tonight.)


So again, likely more information than anyone really wants to know…

If a questionable J20 RAM slot wasn’t already enough to contend with here… a much closer inspection of the original (2) 1 GB modules provided yet another concern.



See that “Big S” on module #2? It’s in slot J23. But when I swap in into J21 — and module #1 into J23… I get a “Finder failure” message upon boot and reboot. (I’ll attempt to attach a SpecTek.pdf file below.) Swap the sticks back and no problem. Hmm?

And then upon a much closer examination of #2’s backside, what’s that? Missing TWO little capacitors? Yet it still seems to work fine, just as long as it remains in the J23 slot - with module #1 in the J21 slot.



Okay, that’s defintely more than enough for now!