Windows 7 Mac Pro Memory Controller problem

Discussion in 'Mac Pro' started by drazyw, Feb 17, 2010.

  1. drazyw macrumors newbie

    Feb 17, 2010
    Ok, So I've got a late 09 Mac Pro running native Windows 7 and I've got a little problem with the memory configuration. It came with 6GB of ram 6x1GB, 3 in each channel. I'm getting a memory error on boot in the system event logs when ever there is memory installed in the B channel. (Dimm slot 5-8) I can run memory in an dimm slot 1-4 but never in any dimm slot on the other channel 5-8. Has anyone else seen this before? I'm also running the latest bootcamp (3.1)

    Here it the error generated.

    A fatal hardware error has occurred.

    Component: Memory
    Error Source: Machine Check Exception

  2. nanofrog macrumors G4

    May 6, 2008
    Does this issue persist, even if you swap the RAM around?
  3. drazyw thread starter macrumors newbie

    Feb 17, 2010
    Yeah, No matter how i configure the ram, it will do it. We've got about 20 machines like this and all of them do the same thing. Use the ram in a single channel config and it's fine with no error. The minute you put any ram into any of slots 5-8 that error will be generated.
  4. TennisandMusic

    Aug 26, 2008
    There are 8 slots? I would look to see how you should be putting in the RAM sticks. I remember when I looked at an X58 board (similar to what you have in there basically), if you had less than six memory sticks, the order you put the stuff in was kinda weird. It wasn't slots 1-5. So there is a chance that the order you need to be inserting the ram is kinda funky.

    Of course, this post could be totally wrong, just a thought. Feel free to deride me if that is the case. :p
  5. nanofrog macrumors G4

    May 6, 2008
    All 20 systems are having the same error?

    So I presume with your various attempts at configuration, the memory that failed in the second bank (5,6,7), will function if installed in the first bank (1,2,3)?

    Assuming this is the case, and it's installed correctly (see below just in case - **), then re-install the RAM in the second bank as well (slots 5 - 7; leaving in the RAM in slots 1 - 3 as well), and restart. While it's doing this, leave the cover off, and check the DIMM LED's. IF they're either bad or not seated properly, then the LED will light up as Red.

    If this happens, and you know the RAM is good (including seated properly), then you've got a bad daughterboard, and the systems will require service (replacement parts). :( That would really suck, and mean that there had to be a bad batch (i.e. bad etching of the PCB) or they were damaged during assembly.

    **Just for reference, 6x DIMM's, you want to have them installed in Slots 1,2,3, and 5,6,7 to allow for triple channel operation (source).**

    Also, just in case you've not done it, try PRAM and SMC resets to make sure that's not causing you any issues/complications.

    Hope this helps. :)
  6. drazyw thread starter macrumors newbie

    Feb 17, 2010
    Yeah, this happens on all 20 systems. It's worth noting that on the systems that are dual booting, OSX reports no issues and memory tests done using windows 7's extended tests result in no errors found.

    Yeah, I've tried all kinda configurations. Even just 1 Dimm in each slot alone by itself. No error will be reported if it's in slot 1-4 but it will generate an error in any slot 5-8. Right now, I'm just thinking it's windows 7 maybe having some issues with the bootcamp drivers or something. It would really suck if all these machines had a problem with them from the factory but I'm not so sure given that some are working just fine with Snow Leopard. (Those that are running it at least) My machine doesn't crash or anything but there are a few that are crashing and they report errors with invalid memory being referenced. (debugging the memory.dmp files) I tested to see if maybe this error was the cause but using them with memory in dimms 1-4 only got rid of the error but didn't stop them from randomly rebooting. That just may be unrelated. Anyway, I'll keep plugging away.
  7. nanofrog macrumors G4

    May 6, 2008
    I guess you could try re-installing Windows using BC 3.0 (to test BC 3.1 as the causality).

    So all the DIMM slots are functional under OS X on all the '09 systems (a little unsure of what you're describing here)?
  8. NoiseDesign macrumors newbie

    Feb 26, 2010
    I seem to be having a possibly related problem on a Quad Core Mac Pro 2.66 GHz (Two identical machines are having this problem).

    I'm installing the 32 bit version of Windows 7 and it seems to run fine up until I start to run the Windows updates. At that point I start to get BSODs during the update process and most of them will not install.

    Bootcamp 3.1 is installed on both machines.

    Now for the reason I think this may be related. Each of these machines have 8 GB of RAM installed using 4 2 GB chips. When I look at the properties of the machine in Windows 7 it reports 8 GB of memory but only 1.99 GB available. Under the 32 bit install I should be seeing 4 GB of the 8 GB of memory. This is Windows 7 Ultimate so I'm not hitting a version restriction.

    This occurs no matter what order I install the chips in, and persists even if I drop back to only 4 GB of RAM installed. I even tried installing the original 3 GB of RAM that shipped with the machine and I still see the same problem.

    This is on the latest revision of Mac Pro, both of these machines were purchased in late September.

    Any thoughts?
  9. nanofrog macrumors G4

    May 6, 2008
    Have you tried backing down to BC 3.0?
    And is Windows on a separate disk or shared on the same disk as OS X?
  10. WonderSausage macrumors member


    Jul 3, 2008
    You will never be able to access 4 GB of RAM under a 32-bit operating system. In x32 architecture the accessible address space is 4 GB. All system and add-in devices need to live within that address space as well, e.g. the 512MB-1GB RAM on a typical video card. Depending on what specific devices are installed, the maximum addressible RAM in a 32-bit system will be between 2 GB and 3.2 GB. Windows 7 will say 4 GB in the properties dialog because it's talking about total RAM installed, not total RAM accessible.

    Modern systems remap the RAM that has been made inaccessible by system config space, up above the 4 GB boundary so it's usable in x64 operating systems. That's why, if you run Windows x64 on a 4 GB RAM system, you generally get a "free" 1 GB or so of RAM that was otherwise unusable. This more than makes up for the slightly larger code size of an x64 OS. This is one reason that nearly 100% of new OEM (non-netbook) PCs preinstalled with Windows 7 are running x64 edition. Nobody runs Windows x32 anymore except to upgrade an existing x32 system (because changing to x64 would require a clean install).
  11. packsherpah macrumors newbie

    Jul 19, 2010
    Take a look at this thread here, I think this is related:

    I have a 2010 mac pro 12 core system which I run bootcamp and I have always gotten the following error in the error log:

    WHEA LOGGER EVENT ID 46: A fatal hardware error has occurred.

    Component: Memory
    Error Source: Machine Check Exception

    Now the thread I linked to above states that dual core xeon motherboards (EVGA SR-2) which is the PC equivalent to the Mac Pro motherboard I think - had the same problems for months, but then they released a new bios and the problem went away. Ofcourse there is no BIOS in boot camp, so I think this error will not be solved until Apple fixes something in Bootcamp. Not sure if this is a well known issue, but I suspect everyone with a dual CPU motherboard on any recent Mac Pro's gets this error or some form of it in Bootcamp running Windows 7. Any thoughts?

Share This Page