Lost a Ram Slot?

aslowdodge

macrumors member
Original poster
Nov 12, 2012
90
9
I have a mac pro 4.1 that I just swapped over processors from 2x2.26 to 2x3.46.
Everything boots up fine and the two new processors show up except now I have one ram slot not recognizing the ram stick.
Originally all 8 slots were filled with 4 gb sticks for a total of 32mb. Now it only shows 28gb and that slot 6 is empty.
Originally after install of new processors it only showed 12 gb (3 ram slots filled), I tightened down the heat sinks so each screw stopped and got 7 slots filled now showing 7x4gb. Slot six shows as empty. I've tried to reseat the ram, swapped the ram 5&6, and 7&6 but still slot 6 not showing any ram. it says empty.
Could this be a bad processor? If so is it processor A or B?
I'm thinking of swapping the processors locations to see if the problem moves the ram slot to a different spot.
I also have this red light which stays on, not sure if it means anything.
Any suggestions?
IMG_2430.JPG
 

tsialex

macrumors 603
Jun 13, 2016
5,297
6,016
Brazil
I have a mac pro 4.1 that I just swapped over processors from 2x2.26 to 2x3.46.
Everything boots up fine and the two new processors show up except now I have one ram slot not recognizing the ram stick.
Originally all 8 slots were filled with 4 gb sticks for a total of 32mb. Now it only shows 28gb and that slot 6 is empty.
Originally after install of new processors it only showed 12 gb (3 ram slots filled), I tightened down the heat sinks so each screw stopped and got 7 slots filled now showing 7x4gb. Slot six shows as empty. I've tried to reseat the ram, swapped the ram 5&6, and 7&6 but still slot 6 not showing any ram. it says empty.
Could this be a bad processor? If so is it processor A or B?
I'm thinking of swapping the processors locations to see if the problem moves the ram slot to a different spot.
I also have this red light which stays on, not sure if it means anything.
Any suggestions?View attachment 814008
If you swap processors and the DIMM slot 6 continues to fail, red light is the fail indicator, you have a problem with your CPU tray, probably a finger on the CPU socket is bent/dirty/etc.
 

aslowdodge

macrumors member
Original poster
Nov 12, 2012
90
9
If you swap processors and the DIMM slot 6 continues to fail, red light is the fail indicator, you have a problem with your CPU tray, probably a finger on the CPU socket is bent/dirty/etc.
If I leave it as is, will this become and issue? Is the CPU socket where the processors sit on top of?
 

tsialex

macrumors 603
Jun 13, 2016
5,297
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If I leave it as is, will this become and issue?
This is the type of thing that is better to find what is causing, you don’t want a computer that has RAM/socket problems.

One thing that you can do is swap the processors, from A to B, if the RAM slot that is not recognized changes, it’s the processor.

Is the CPU socket where the processors sit on top of?
Yes.
 

skizzo

macrumors regular
Apr 11, 2018
229
59
given your CPU's came with some poorly chosen placements for stickers I am suspicious there is contamination of some sort. I would investigate the CPU/socket that is associated with the faulty RAM DIMM slot
 

aslowdodge

macrumors member
Original poster
Nov 12, 2012
90
9
As I look into the computer I have two heat sinks for the processors.ram is in groups of 4. Does each processor control a row of ram slots? If so, the processor on my right, is that controlling the ram slots 5 through 8 right in front of me or the ram slots 1 to 4 to the left behind the left side heat sink. This way I can maybe determine which processor is bad if that is the case. Right now slot 6 is bad so I’m trying to determine which side is bad
 

tsialex

macrumors 603
Jun 13, 2016
5,297
6,016
Brazil
As I look into the computer I have two heat sinks for the processors.ram is in groups of 4. Does each processor control a row of ram slots? If so, the processor on my right, is that controlling the ram slots 5 through 8 right in front of me or the ram slots 1 to 4 to the left behind the left side heat sink. This way I can maybe determine which processor is bad if that is the case. Right now slot 6 is bad so I’m trying to determine which side is bad
Download the Service Manual for 2009 Mac Pro, you will find everything to diagnose your Mac Pro.

CPU A - DIMM slots 1 to 4
CPU B - DIMM slots 5 to 8

Screen Shot 2019-01-04 at 13.07.36.png

MP51 - dual cpu tray.png
 
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aslowdodge

macrumors member
Original poster
Nov 12, 2012
90
9
Awesome. Thanks. I’m going to reverse spots and if the problem changes and if it does pull them and put the old processors back.
 

flowrider

macrumors 603
Nov 23, 2012
5,538
1,964
When I upgraded my DP cMP 5,1 I had a similar issue, I lost one RAM slot. I use only 3 for each of the CPUs. Anyway I swapped the CPUs, and the problem followed one of the CPUs. I contacted the seller, who replaced it. When the new one arrived I replaced the errant CPU, Problem Solved. I then returned the defective CPU to the seller.

Lou
 

aslowdodge

macrumors member
Original poster
Nov 12, 2012
90
9
When I upgraded my DP cMP 5,1 I had a similar issue, I lost one RAM slot. I use only 3 for each of the CPUs. Anyway I swapped the CPUs, and the problem followed one of the CPUs. I contacted the seller, who replaced it. When the new one arrived I replaced the errant CPU, Problem Solved. I then returned the defective CPU to the seller.

Lou
Well I switched sides and the problem followed the cpu, just like yours. The missing ram is now in slot 2 instead of 6.
I doubt the seller will exchange or refund since I delidded it. I just ordered another single one from China from a different vendor since the last one put the stickers onto the cpu as I illustrated on my other thread. That sticker was really stuck on and had to be taken off in many tiny pieces.
Well another $80 thrown out.
Did you continue to use the defective one? I'm wondering if I can just use this as is for a few weeks till the replacement gets here. Otherwise I will take them out and put in the old 2.26 processors
 

pl1984

Suspended
Oct 31, 2017
2,230
2,603
Well I switched sides and the problem followed the cpu, just like yours. The missing ram is now in slot 2 instead of 6.
I doubt the seller will exchange or refund since I delidded it. I just ordered another single one from China from a different vendor since the last one put the stickers onto the cpu as I illustrated on my other thread. That sticker was really stuck on and had to be taken off in many tiny pieces.
Well another $80 thrown out.
Did you continue to use the defective one? I'm wondering if I can just use this as is for a few weeks till the replacement gets here. Otherwise I will take them out and put in the old 2.26 processors
Since I'm late to that discussion I'll just throw this out here: Next time just heat the sticker up with a hair dryer. That should loosen the bond and allow easier removal.
 

aslowdodge

macrumors member
Original poster
Nov 12, 2012
90
9
Since I'm late to that discussion I'll just throw this out here: Next time just heat the sticker up with a hair dryer. That should loosen the bond and allow easier removal.
That’s a good idea, wish you got here earlier. I will say that the stickers were pushed on so hard using an xacto knife tip didn’t help they were pushed on so it wasn’t just on the high points, but glued to the flat areas too.
I doubt I’ll get my refund since I decided both of them, but I can’t help think the sticker removal was a possible culprit in the one not working.
They could have easily put the sticker on the heat sink or on the part of the board without delicate components.
 

aslowdodge

macrumors member
Original poster
Nov 12, 2012
90
9
Just an update. I got another processor to replace the one suspect one I got. I just got through delidding it and was ready to replace the bad one, but today all ram slots are working. Strange.
I guess I'll just put the replacement one off to the side and keep an eye out on the ram situation for a while
 

aslowdodge

macrumors member
Original poster
Nov 12, 2012
90
9
Well now for some reason I am back to my missing ram slot.
I replaced the bad processor with the replacement and everything ran fine . Had all ram recognized and both processors recognized. So now I have my one good processor and replacement processor and all is well. Started and restarted multiple times yesterday and all was fine. Installed firmware 140.0.0.0.0, added my new saphire pulse graphic card, and samsung 970pro in a PX1 as boot. Everything worked great. Started and restarted to test.
Today I go to start up and nothing...
I reinstall the bad processor and take out the replacement and I am back to not recognizing Dimm 2, but at least I'm up and running again.


1. Can I run the mac from here on out with it only recognizing 7 of 8 ram slots as filled?
2. If so is it better to give up ram slot 2 or ram slot 6?
3. How much is ram compromised. Am I just at 28 now instead of 32gb, or does that one ram slot not recognizing foul up some kind of interdependency? I know that your supposed to fill ram slots in a certain order.
4. At this point I'm hesitant about ordering yet another replacement processor so trying to see if I can get by with what I have or buy new ram. I have the 1066 speed ram and thought of setting up processors to have ram slot 6 not recognized. Then pull all my ram out and buy 2 16gb 1333 and just put in slots 1 and 2 and get my 32 gb or ram with just 2 slots used.

Any thoughts or suggestions?
 

StudioT

macrumors newbie
Oct 10, 2018
3
0
Well I switched sides and the problem followed the cpu, just like yours. The missing ram is now in slot 2 instead of 6.
I doubt the seller will exchange or refund since I delidded it. I just ordered another single one from China from a different vendor since the last one put the stickers onto the cpu as I illustrated on my other thread. That sticker was really stuck on and had to be taken off in many tiny pieces.
Well another $80 thrown out.
Did you continue to use the defective one? I'm wondering if I can just use this as is for a few weeks till the replacement gets here. Otherwise I will take them out and put in the old 2.26 processors
I was originally going to say your heat sinks aren’t seated right. However you have swapped the CPUs over and the problem remains. You could try cleaning the bottom of the chip with isopropyl. If you are convinced the seller has sent you a dodgy chip I see no harm in relidding it and sending it back.

If you do a good enough job no one will ever know. If the seller removes the lid to look at it, it’s his word against yours. All you need is thermal paste and black gasket sealant.
 

LittlePaul

macrumors member
Mar 15, 2014
49
1
I have the same problem.
After upgrade the cpu the slot 1 not work.
I have swapped the CPU but always the slot 1 not work.. the CPU work fine!
when I reassembled the cpus also slot 2, in addition to slot1, did not work. By loosening the screws, however, slot 2 has resumed functioning. I tried then to loosen again to see if even slot 1 returned to work but I could not.
Other ideas?
 

pl1984

Suspended
Oct 31, 2017
2,230
2,603
I was originally going to say your heat sinks aren’t seated right. However you have swapped the CPUs over and the problem remains. You could try cleaning the bottom of the chip with isopropyl. If you are convinced the seller has sent you a dodgy chip I see no harm in relidding it and sending it back.

If you do a good enough job no one will ever know. If the seller removes the lid to look at it, it’s his word against yours. All you need is thermal paste and black gasket sealant.
IMO this is bad advice. A buyer shouldn't try deceiving a seller for damage potentially caused by the buyer.
 
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aslowdodge

macrumors member
Original poster
Nov 12, 2012
90
9
Just an update
It definitely the processor. The missing ram slot follows the processor location. So I either have ram slot 2 or 6 showing as empty despite ram being installed. So I have 7 of 8 ram slots usable.

No one here know the answer of how this affects anything

According to Apple you install RAM in this order:
Preferred Memory Slot Population for Dual-Processor Mac Pro
  • Two memory modules: Slots 1 and 2.
  • Three memory modules: Slots 1, 2, and 3.
  • Four memory modules: Slots 1, 2, 5, and 6.
  • Six memory modules: Slots 1, 2, 3, 5, 6, and 7.
  • Eight memory modules: Slots 1, 2, 3, 4, 5, 6, 7, and 8.
My solution so far was to install processors so ram slot 6 was the problematic one.
I then pulled all 8 x 4gb dimms out and installed 3 x 16 gb ram. But before I did this one day all 8 slots reappeared. I still pulled all 8 out and install the new ones since they are faster and more memory.

So now I have three memory modules in Slots 1, 2, and 3 avoiding the problematic number 6.

Since the computer had now recognized all 8 slots Just for fun I bought 3 more 16gb and added them into 5, 6, and 7.
I started up and all 6 dimms were recognized. I now had 6 x 16gb.
Later that day photoshop had an issue so I rebooted and slot 6 went missing again, So I now show 5 x 16gb with slot 6 not there again.

Once again, does anyone see any issues running it this way? Or should I pull the last 3 out and just run 3 x16gb in Slots 1, 2, and 3?

I'm pretty sure I didn't damage anything on delidding. It went pretty easily. I had ordered another processor which didn't work at all. So after all this I still show 2 x 3.46 and at worse will have 48gb of ram