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Mac Pro RAM failed Power On Self-Test - Memory

MythicFrost

MythicFrost

macrumors 68040
Original poster
Mar 11, 2009
3,940
38
Australia
Hi,

My Mac Pro has failed the Power On Self-Test. The 'failure type' is memory, and it says it's DIMM 1/DIMM Riser B and DIMM 3/DIMM Riser B. From time to time it's been restarting out of no where, and it was in little a restart loop a few minutes ago.

Is this likely just the RAM failing? I'm going to just remove the RAM from those slots in a minute. That would leave me with two 4GB modules in Riser B, and four 2GB modules in Riser A.

EDIT: It's the 2008 model.
 
Last edited:
DanielCoffey

DanielCoffey

macrumors 65816
Nov 15, 2010
1,207
30
Edinburgh, UK
One thing to check while you are in there is dust.

Get the tray slid out, remove all the ram (keep them in the same order) and vacuum or air-can the board. If you have a soft eraser, gently stroke down the gold contacts of the ram to remove dust and oxidation and brush off any eraser crumbs (use a tissue or small brush, not fingers - grease and static, remember). Put the memory back into the original slots and see if that has resolved the issue.

If it still fails, swap the pairs over and see if the fault moves with the ram or stays with the slot.

If it is the ram, check if you have branded ram with a lifetime warranty and exercise it.
 
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MythicFrost

MythicFrost

macrumors 68040
Original poster
Mar 11, 2009
3,940
38
Australia
DanielCoffey said:
One thing to check while you are in there is dust.

Get the tray slid out, remove all the ram (keep them in the same order) and vacuum or air-can the board. If you have a soft eraser, gently stroke down the gold contacts of the ram to remove dust and oxidation and brush off any eraser crumbs (use a tissue or small brush, not fingers - grease and static, remember). Put the memory back into the original slots and see if that has resolved the issue.

If it still fails, swap the pairs over and see if the fault moves with the ram or stays with the slot.

If it is the ram, check if you have branded ram with a lifetime warranty and exercise it.
Click to expand...
All right, thanks for that. Hopefully it'll just be dust.
 
G

gpzjock

macrumors 6502a
May 4, 2009
798
33
I have had 2 RAM modules out of 8 fail in 4 years, both times on the same slot B2. Both modules were replaced for the price of postage by Memory America. MP 3,1 memory runs very hot, 70-80 degrees C is normal in an ambient temp of about 24-26. If you let the air flow clog up with dust the increased temps make failure more likely. I clean my case out every year with a compressed air line. After each annual clean the average RAM module temp drops ~10 degrees. I use the freeware version of Temperature Monitor to keep an eye on it.
 
Last edited:
W

Wrathy

macrumors newbie
Aug 8, 2019
2
0
Hi MythicFrost, did you ever resolve this?
I have a MacPro 3, 1 that goes into this same restart loop.
I've checked the RAM (Rember Test) and replaced the HD.
I thought my issue was with a failing old monitor that I replaced, that was triggering the restarts?

Please let me know if you've had any luck or what your prescription might be!

THANKS!!!

MythicFrost said:
Hi,

My Mac Pro has failed the Power On Self-Test. The 'failure type' is memory, and it says it's DIMM 1/DIMM Riser B and DIMM 3/DIMM Riser B. From time to time it's been restarting out of no where, and it was in little a restart loop a few minutes ago.

Is this likely just the RAM failing? I'm going to just remove the RAM from those slots in a minute. That would leave me with two 4GB modules in Riser B, and four 2GB modules in Riser A.

EDIT: It's the 2008 model.
Click to expand...
 
MythicFrost

MythicFrost

macrumors 68040
Original poster
Mar 11, 2009
3,940
38
Australia
Wrathy said:
Hi MythicFrost, did you ever resolve this?
I have a MacPro 3, 1 that goes into this same restart loop.
I've checked the RAM (Rember Test) and replaced the HD.
I thought my issue was with a failing old monitor that I replaced, that was triggering the restarts?

Please let me know if you've had any luck or what your prescription might be!

THANKS!!!
Click to expand...
Hmm it was quite some time ago. I think it was the RAM. I tried booting with only 2/4 in different combinations until I found a module that wouldn't boot. I'd recommend trying the same if you can. But yeah it was so long ago I don't recall well.
 
W

Wrathy

macrumors newbie
Aug 8, 2019
2
0
MythicFrost said:
Hmm it was quite some time ago. I think it was the RAM. I tried booting with only 2/4 in different combinations until I found a module that wouldn't boot. I'd recommend trying the same if you can. But yeah it was so long ago I don't recall well.
Click to expand...

Hey Thanks for the reply, I really appreciate it.

Turns out it was bad RAM, although it passed the REMBER test. Only way I found out was I was checking all the fan speeds with the computer open, and there was a red light on the lower DIMM panel. Never would have seen that otherwise.
 
MythicFrost

MythicFrost

macrumors 68040
Original poster
Mar 11, 2009
3,940
38
Australia
Wrathy said:
Hey Thanks for the reply, I really appreciate it.

Turns out it was bad RAM, although it passed the REMBER test. Only way I found out was I was checking all the fan speeds with the computer open, and there was a red light on the lower DIMM panel. Never would have seen that otherwise.
Click to expand...
Yes actually, now that you mention it I may also have spotted a red light on one of the panels. Glad you got it sorted.
 
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