Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

CPU Change - 5,1 Mac Pro - Problem - HELP

flowrider

flowrider

macrumors 604
Original poster
Nov 23, 2012
7,439
3,089
This afternoon, for the second time in a year, I changed the CPUs in my Dual processor 5,1 Mac Pro. I went from my W5590s to X5677s (stayed with 4 core) but a bit faster and more L3 cache and newer architecture.

Anyway, my first Transplant went without a hitch. This time, I finished up in less than 30 minutes, and thought everything was fine. I restarted, and so far so good. When I went to check in "About This Mac" I only had 20GBs or RAM. I have 24GBs installed. 6, 4GB DIMMS. I narrowed it down to slot 3.

I then switched the DIMMS around, and still only 20GBs, and slot 3 still the offending slot. I cleaned the offending slot with some air and there is no dust, I moved the DIMMS around again, and I also tightened the heatsink associated with the CPU that controls that set of 3 DIMMS. Restarted, and still slot 3 is showing MT.

Before the CPU swap, all 24GBs were recognized. Could the new CPU have a 3rd channel memory fault and still work?

This was supposed easy, it's a 5,1 for gosh sake. The first swap was a piece of cake. I probably should have left well enough alone.

Anybody have any ideas??????

Lou
 
It's either the CPUs or the pins.

Either switch back to old CPUs or switch the CPUs themselves.

And don't complain it's a pain. Doing this in a 5,1 is like pouring yourself a cup of coffee versus a Dual CPU 4,1 which is planting the coffee tree, growing it, harvesting the beans, roasting them and then inventing the coffeemaker.
 
I had (or have - i don't know) a similar problem with my 4,1 Mac Pro (upgraded to 5,1), after i replaced the old Xeon W3540 2.93 GHz with a W3690 3.46 GHZ.

First all was fine, but a day after installation the DIMM on slot 3 disappeared, had only 16 GBs instead of 24 GBs. After a reboot my Mac Pro showed all three DIMMs again. Then a day later the same event happened. Could be solved with a restart again.

However the last 4 days, it did not happen again. Uff...

Is there a need for action for me? Or should I wait as long as it does not happen again? :confused:

By the way: I like the new processor, Geek bench
Single Core old 2'126 -> new 2'656 = + 25%
Multi Core old 8'036 -> new 14'664= + 82% :cool: No need for a nMp 2013 for the time being.
 
Last edited:
i didn't even know about the X5677 cpu's until now... wish i had know that before my X5550-X5670 upgrade, they are seriously cheap and performance in single core due to higher clock speed and turbo boost beats the X5670.
 
I had almost the same problem. I have a single processor Mac Pro 4,1 and when I upgraded the CPU, slot one wouldn't register any RAM. In my case it turned out one (!) of the pins in the CPU socket was slightly bent. I straightened it out and all four slots worked. I haven't had an issue since. Have you checked the socket to see if any pins are bent or slightly misaligned?
 
Lou, there's always some mystery/weirdness/magic/whateweryoucallit* involved in CPU+RAM upgrades. I've done a number of 4,1->5,1 single and dual CPU upgrades, and I encountered problem like this just once.

My test mule is 4,1 flashed to 5,1 with W3570. When I put W3690 in this machine (not the first time), it lost one of 3 16GB 1066 sticks. No matter what I tried, it always was failing to recognize this one and only 16GB stick. Red light followed the module, so message should be clear = dead stick. But this module worked A-OK with W3570 in whatever slot I was choosing. 1333 MHz sticks (all 16GB ones) worked as they should.
I sold this specific W3690 and 1333 sticks then put 3580 in a MP, and suddenly this "bad" stick started to work. Few days ago I got another W3690 and guess what: all my 1066 16GB sticks do work, including this "bad" one.

You have a 5,1, so you don't need to count the wrench turns, that's sure.
 
^^^^Yes, I've got the red LED also. I have a replacement X5677 in it's way to me know. Thanks for your input.

Lou
 
Thank you for feedback!

@ 666sheep: Maybe i've got your old W3690. ;-)

And yes, I have three 8 GB 1066 MHz DIMMS. They worked well with my old W3540.

The stick in slot 3 disappeared again. So i changed the stick in slot 2 to slot 3, and vice versa. So far no more problems.

666sheep said:
1333 MHz sticks (all 16GB ones) worked as they should.
Click to expand...

I will wait a while and if no stick will disappear again. But soon I'm going to buy three 1333 MHz 16 GB sticks, which should work.
 
Last edited:
Replacement CPU came in the mail today. All is GOOD - The errant RAM is back!

Lou
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back