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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