MP 1,1-5,1 Mac Pro 1,1 not recognizing RAM on DIMM2 and DIMM4 on raiser A

[Tommydj10]

I have a Mac Pro 1,1 -> 2,1 with 8x4GB ram sticks. As it’s usual for these machines I tried to swap them between raisers, slots, etc and consistently the raiser A (the top one) keeps not recognizing any RAM in both DIMM2 and DIMM4. While the same configuration in the raiser B is always fully recognized. What could be the issue?

The ram sticks are all matched pairs of 4GB 2Rx4 PC2-5300F-555-11
4x : Samsung M395T5160CZ4 -CE65
2x : Hynix HYMP351F72AMP4D2-Y5
2x : Samsung M395T5160QZ4-CE68

 

[Nguyen Duc Hieu]

I have a Mac Pro 1,1 -> 2,1 with 8x4GB ram sticks. As it’s usual for these machines I tried to swap them between raisers, slots, etc and consistently the raiser A (the top one) keeps not recognizing any RAM in both DIMM2 and DIMM4. While the same configuration in the raiser B is always fully recognized. What could be the issue?

The ram sticks are all matched pairs of 4GB 2Rx4 PC2-5300F-555-11
4x : Samsung M395T5160CZ4 -CE65
2x : Hynix HYMP351F72AMP4D2-Y5
2x : Samsung M395T5160QZ4-CE68

Aged components is the issue.

 

[Tommydj10]

Aged components is the issue.

Yes, a 2006 computer is old, but it's working great with 2x 4 cores CPUs, 32GB of RAM (even though now it can only see 16GB), an updated GPU with 2GB of GDDR5, and updated OS X to El Capitan. Even an old Mac Pro from 2006, if properly updated can perform great in 2022, and this is the place to fix issues with "aged components" and give a new life to old hardware.

 

[Nguyen Duc Hieu]

Yes, a 2006 computer is old, but it's working great with 2x 4 cores CPUs, 32GB of RAM (even though now it can only see 16GB), an updated GPU with 2GB of GDDR5, and updated OS X to El Capitan. Even an old Mac Pro from 2006, if properly updated can perform great in 2022, and this is the place to fix issues with "aged components" and give a new life to old hardware.

Please enlighten me on how you fix a hardware problem like non-working RAM slot.
I have a bunch of mainboards with that problem.

 

[Tommydj10]

Please enlighten me on how you fix a hardware problem like non-working RAM slot.
I have a bunch of mainboards with that problem.

If I knew it I didn’t have to post a question here 😅 Mac Pro 1,1 are notoriously picky with RAM so maybe someone who faced a similar issue could “enlighten us”. Also what are your mainboards, a general PC, a Mac Pro, which year? Also what issue are you having, you can’t see DIMM2 and DIMM4 on raiser A as well, different raiser, different DIMM, something totally different? If you share what you got maybe we can all benefit from it.

 

[Nguyen Duc Hieu]

If I knew it I didn’t have to post a question here 😅 Mac Pro 1,1 are notoriously picky with RAM so maybe someone who faced a similar issue could “enlighten us”. Also what are your mainboards, a general PC, a Mac Pro, which year? Also what issue are you having, you can’t see DIMM2 and DIMM4 on raiser A as well, different raiser, different DIMM, something totally different? If you share what you got maybe we can all benefit from it.

No, I meant that you would not be able to fix a dead RAM slot.
I have several PC mainboard with one or two dead RAM slot, and couldn't fix it anyhow.

 

[Tommydj10]

But the same ram slot if I move the raiser from A to B will work, all 4 DIMMs are recognized. And in the raiser A it’s not completely dead, it still recognizes DIMM1 and DIMM3. If the motherboard connection for raiser A was dead it would recognize 0 DIMMs, right? Can a motherboard raiser connection be dead only for selected DIMMs?

 

[Nguyen Duc Hieu]

But the same ram slot if I move the raiser from A to B will work, all 4 DIMMs are recognized. And in the raiser A it’s not completely dead, it still recognizes DIMM1 and DIMM3. If the motherboard connection for raiser A was dead it would recognize 0 DIMMs, right? Can a motherboard raiser connection be dead only for selected DIMMs?

If you try the second RAM raiser on slot A, will it be the same issue? (DIMM 1 & DIMM 3 are not recognized)
If you install RAM on DIMM 1 & DIMM 3 only, will they be recognized?

If it is, then there is something wrong on the logicboard or the CPU. (maximum RAM support is limited)

If you are using the quad-core CPUs, you can exclude the cause from CPU limitation.

Without adequate information, I can only guess and assume stuffs, can't help you analyze the exact cause. Look to my signature. I have the same MP1,1-> 2,1 and it can run 8x4GB DIMM smoothly.
The Youtuber Hrutkay Mod has already tried 8 x 8GB of FB-DIMM in his MP1,1.

 

[Tommydj10]

If you try the second RAM raiser on slot A, will it be the same issue? (DIMM 1 & DIMM 3 are not recognized)
If you install RAM on DIMM 1 & DIMM 3 only, will they be recognized?

If it is, then there is something wrong on the logicboard or the CPU. (maximum RAM support is limited)

If you are using the quad-core CPUs, you can exclude the cause from CPU limitation.

Without adequate information, I can only guess and assume stuffs, can't help you analyze the exact cause. Look to my signature. I have the same MP1,1-> 2,1 and it can run 8x4GB DIMM smoothly.
The Youtuber Hrutkay Mod has already tried 8 x 8GB of FB-DIMM in his MP1,1.

The Mac Pro is from 2006 1,1 flashed to 2,1. I upgraded both CPUs to quad core X5355.

The issue is in the Raiser A (top one) DIMM2 and DIMM4 are not recognized. And the problem is always on the top raiser, no matter if I swap the raiser cards.

This are all the possible cases:

a. All raiser card are filled up with 8 DIMMs:
RESULT: raiser A sees no DIMMs it says all empty. Raiser B is recognizing all 4 DIMMs. Same result if I swap the raisers. Same result if I swap the DIMMs.

b. Only one raiser card with 4 DIMMs is plugged in.
RESULT: if plunged in raiser B (bottom) all DIMMs will be recognized. If plugged in raiser A (top) only DIMM1 and DIMM3 are recognized, DIMM2 and DIMM4 show empty.

c.
Only one raiser card with 2 DIMMs (in DIMM1 and DIMM2) is plugged in. DIMM3 and DIMM4 are left empty
RESULT: if plunged in raiser B (bottom) all DIMMs (2) will be recognized. If plugged in raiser A (top) only DIMM1 only is recognized, DIMM2 show empty.

d. Both raiser cards are filled up with 2 DIMMs each, in position DIMM1 and DIMM2:
RESULT: raiser A sees no DIMMs it says all empty. Raiser B is recognizing all 2 DIMMs. Same result if I swap the raisers. Same result if I swap the DIMMs.

e.
Both raiser cards are filled up with 2 DIMMs each, in position DIMM1 and DIMM3:
RESULT: All DIMMs are correctly recognized this time, in both raisers.

If you need more info let me know.

Is there any hardware test to perform to analyze more in depth what goin on? Or anything at all to do to understand what’s happening?

 

[Nguyen Duc Hieu]

Is there any hardware test to perform to analyze more in depth what goin on? Or anything at all to do to understand what’s happening?

I don't think there are any other tests you can run.
Looking from your results, the issues may reside on the logic board (highly) or CPUs (very low).
If you have time, swap the CPUs to see if the issue moves from RAM slot A to RAM slot B.
If it does, then you can conclude that the CPU is the issue, logic board is OK.
Otherwise, conclude that the logic board is bad and you have to leave with only 6 slot of RAM, which are quite adequate.
You can compensate the capacity by using 8GB FB-DIMM.

 

[Tommydj10]

I don't think there are any other tests you can run.
Looking from your results, the issues may reside on the logic board (highly) or CPUs (very low).
If you have time, swap the CPUs to see if the issue moves from RAM slot A to RAM slot B.
If it does, then you can conclude that the CPU is the issue, logic board is OK.
Otherwise, conclude that the logic board is bad and you have to leave with only 6 slot of RAM, which are quite adequate.
You can compensate the capacity by using 8GB FB-DIMM.

yeah it's most probably the motherboard then. But that's so weird that on the same connector, in my case the top raiser, some DIMMs work and some don't. I would expect the whole connection dies all together. Has this ever happened to anyone?

Also, unfortunately max 4 DIMMs can be used. I put 2 DIMMs on Raiser A (any configuration) and 4 DIMMs on raiser B (full), only the 4 on raiser B will be seen. So I can either put 2 on raiser A and 2 on raiser B (position DIMM1 and DIMM3) or nothing on raiser A and 4 DIMMs on raiser B. Which configuration would be faster?

Is there a way to test the hardware? maybe it's a random capacitor that is going old and not giving the right voltage, and I could fix it by replacing that only.