MP 1,1-5,1 Mac Pro 5,1 front panel light error code

[BlueMacawBird]

I just added a dual processor CMP 5,1 to my pile, a 2.4ghz eight core machine. It came to me with 16GB of memory, four fours. The machine runs fine. However, when I added memory the machine will not start. The front panel light flashes steadily, there is no boot beep, and there are no error LEDs illuminated on either the backplane or the processor tray. All the memory is known good and meets spec. I have tried several sets of memory. I could not find anything about the front panel error codes in my Apple technicians guide; if anyone can tell me what page to find it on please let me know.

My worst thought is that one of the second set of four memory slots is bad, probably either slot three or seven (I tried a six module installation and the error did not go away). Any suggestions would be appreciated; I just got this computer off the world famous auction site, and it will have to go back if it is defective.

Thanks,

John

 

[KeesMacPro]

I could not find anything about the front panel error codes in my Apple technicians guide; if anyone can tell me what page to find it on please let me know.

Have you tried installing only the 4 new RAM modules?
My guess is that the old 4x4 and the new 4x4 are different types and not possible to mix...(?)

Anyway the Technician Guide pag.27 says:

 

[KeesMacPro]

My worst thought is that one of the second set of four memory slots is bad, probably either slot three or seven

I assume you could test that by installing the RAM modules "the wrong way":
-the old 4 known working RAM modules in slot 1,2,3,4
-the old 4 known working RAM modules in slot 5,6,7,8

As soon as the MP booted, there should popup a little screen telling you the RAM is not installed in the optimal configuration, this is normal.
At least you could see that way (in Hardware Info) if the slots are working.

 

[BlueMacawBird]

I have tried every possible combination of the memory modules and nothing will work in the second set of four memory slots. All the memory is correct for the machines. All the memory is ECC (that was one of the first things I checked). I have one more set of memory that I will try later today.

Thanks for the page from the technicians guide. It is different from page 27 on my copy of that document (revision 2010-12-06) which shows the processor board.

Oddly, the front panel light behavior that I am seeing is not described on your document. My light flashes steadily, not in a sequence of three flashes. And there is no activity on the error LEDs inside the machine.

 

[BlueMacawBird]

This morning the mailman brought me a set of memory chips that I had bought earlier in the week. Using them I was able to get the machine to recognize all eight memory slots and the installed chips. The chips that had come with the machine still caused the problem if I tried to use them in combination with my new memory, so there does indeed seem to be some kind of incompatibility issue beyond having the chips meet basic specs.

 

[tsialex]

This morning the mailman brought me a set of memory chips that I had bought earlier in the week. Using them I was able to get the machine to recognize all eight memory slots and the installed chips. The chips that had come with the machine still caused the problem if I tried to use them in combination with my new memory, so there does indeed seem to be some kind of incompatibility issue beyond having the chips meet basic specs.

Nehalem and Westmere Xeons memory support are a very complex topic, without entering too much in detail, there are 3 main types of DRAM that can be used with a MP5,1:

• UDIMM non-ECC (normal PC memory)
• UDIMM ECC (Server and workstation memory)
• RDIMM ECC (Server and workstation memory)

You can't mix different types, all memory installed have to be of the same type/spec.

Another thing, MP5,1 memory needs to be of 2R4 ranking, the most usual registered 1333MHz 16GB and 8GB DIMMs on the market today, 4R4 ranking, most of the time don't work at all or only work at 800MHz.

Last thing, there is a limit for the quantity of memory chips that can be addressed too, some DIMMs don't work because they have too much memory chips.

 

[BlueMacawBird]

Thanks, that explains a lot. I've been lucky and all the memory I've bought has worked OK. I knew about the ECC part, and not mixing non ECC with ECC, but I had not heard of the UDIMM and RDIMM difference. I was always buying sets of four DIMMs since I had single processor machines. Now that I have the one dual processor machine I'll have to be more specific when adding memory.