Operating System Not Found after RAM upgrade?
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Thread: Operating System Not Found after RAM upgrade?

  1. #1
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    Operating System Not Found after RAM upgrade?

    Help! some time ago I bought a 256MB memory upgrade for my laptop, taking the total from 256MB to 512MB. After fitting the memory, the laptop won't boot properly as described below. Can you help me resolve the problem?

    The laptop is a Dell Inspiron 2500 running Windows ME with flash BIOS version R52472. It doesn't have any other operating systems or non-standard boot managers installed. The memory is a 256MB stick from Crucial (BG111MQ.7X CT32M64S4W8E.16FG), as recommended by the Crucial online memory selector.

    With the extra memory installed, when I turn the laptop on the message 'Operating System not found' appears after the BIOS initialisation where I would normally expect to see the Windows ME splash screen. The BIOS setup screen shows that the BIOS has detected the extra memory.

    The system will boot successfully if I put a bootable Windows ME installation CD in the CD drive, and select 'boot from Hard Disk' from the menu offered by the CD boot manager. Having booted like this the system works fine; there are no device conflicts, the system property sheet shows the extra memory and everything behaves as normal. I can also see from the System Monitor application that it is making use of the extra memory.

    My tentative conclusion is that the problem is associated with either the Master Boot Record on the disk drive, or the contents of the boot sector.

    I've discovered that I can effect a temporary repair by booting from a startup floppy disk, and running 'FDISK/MBR' and 'SYS C:'. It will then boot from the hard disk as normal once, but at the next reboot the 'Operating System not found' error comes back. This seems to suggest that the MBR and/or boot sector are being damaged each time the system boots with the extra memory in.

    If I take the extra memory out I still get the 'Operating System not found' error, but if I run 'FDISK/MBR' and 'SYS C:' it boots successfully and the problem doesn't come back (as long as I leave the extra memory out!).

    If I remove the original 256MB memory card and fit the new one in its place, it works fine. I also tried swapping the old and new memory cards over but this still leads to the 'Operating System not found' error. In other words, the two memory cards seem to behave identically, and the problems occurs whenever I have both fitted.

    I've run scandisk, the Dell hardware diagnostic tests, and various brands of antivirus scanners. None of these have shown any faults with the disk, RAM, processor etc.

    Do you have any suggestion to resolve this problem? I do need the extra memory, but it's no good unless I can get the PC to boot!

    Thanks for reading!

  2. #2
    Registered User slgrieb's Avatar
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    This is the sort of weirdness I usually associate with with incompatible modules. Are you using a Crucial CT484746? Please double check your part no.

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    There are half a dozen part numbers on each side, but the bit that seems to make most sense says:

    PC100-222-620 256MB SYNCH 100MHz CL2

    It doesn't say 'CT484746' on it anywhere, but I see that is the part number that Crucial's web site recommends now.

    Interestingly, the spec for CT484746 indicates that it's designed for PC133 but my stic says 100MHz. That doesn't look right! I guess it's possible that the laptop will tolerate either memory speed but not the mixture? Don't understand how this would cause the specific boot-time problem I'm getting and then work fine subsequently, but at least it's something I can investigate.

    Any other thoughts? Thanks for the help so far!
    Last edited by DumbNewbie; January 5th, 2006 at 06:37 PM.

  4. #4
    Registered User Sandwich's Avatar
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    It sounds to me like you may have either a bad stick of memory or a bad mb memory slot. There is a downloadable program for checking memory that you can use to rule out the problem. You can either put the program on a floppy and boot from there or put it on cd and boot from there. It's memtest 86 here.
    http://www.memtest86.com/
    HP Laptop 6830s with 4 Gbs ram and a 250gb HDD I run Vista business 64bit. But I have some old computers too.

  5. #5
    Banned slavedriver's Avatar
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    Cool

    Quote Originally Posted by DumbNewbie
    There are half a dozen part numbers on each side, but the bit that seems to make most sense says:

    PC100-222-620 256MB SYNCH 100MHz CL2

    It doesn't say 'CT484746' on it anywhere, but I see that is the part number that Crucial's web site recommends now.

    Interestingly, the spec for CT484746 indicates that it's designed for PC133 but my stic says 100MHz. That doesn't look right! I guess it's possible that the laptop will tolerate either memory speed but not the mixture? Don't understand how this would cause the specific boot-time problem I'm getting and then work fine subsequently, but at least it's something I can investigate.

    Any other thoughts? Thanks for the help so far!
    If your notebook specks require PC133 ram PC100 won't work.

  6. #6
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    Seems that the FSB speed is 100 Mhz on this machine so in theory the PC100 memory is the correct spec. And the Dell hardware diagnostic doesn't indicate any memory faults. Everything seems fine, apart from the startup problem.

  7. #7
    Banned slavedriver's Avatar
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    Cool

    Quote Originally Posted by DumbNewbie
    Seems that the FSB speed is 100 Mhz on this machine so in theory the PC100 memory is the correct spec. And the Dell hardware diagnostic doesn't indicate any memory faults. Everything seems fine, apart from the startup problem.
    Then the added Ram is PC133 ? look on their website the specifications on the PC133 if its EDO and the PC100 is Unbuffered that will cause the problem,
    PC133 is compatable if its the same type DIMM.

  8. #8
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    The laptop is PC100, the memory they supplied is PC100. Crucial now recommend either PC100 or PC133, but neither of the part numbers they recommend match what they supplied. This isn't unreasonable because it's been some time since I bought the memory and the supply situation could have changed in the meantime. But it could also be that the memory they supplied is wrongly specced in some other respect.

    I'm not familiar with EDO or the significance of buffered versus unbuffered memory, and I have no idea which I need and which I have. Do you know where I can find out more about this issue?

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  10. #10
    Registered User slgrieb's Avatar
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    Hello, Newbie! If you have a CT32M64S4W8E memory module, it absolutely will not run along with the original memory in your Inspiron. The E in the part number indicates that the module is EDO, not Fast Page memory. You can't mix the two types in a system.

    Sounds like you may have had this module long enough to forget a refund or replacement, so looks like you're stuck with buying another module. The CT484746 will work fine with your existing memory. The reason Crucial lists a 133 module for your machine rather than a 100 is just that most mfgs have stopped production on 100 MHz memory. The new PC133 module will just run at 100 MHz.

  11. #11
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    I think you've hit the nail on the head slgrieb, I'll ask Crucial to send me a CT484746 module. Thanks for the help.

  12. #12
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    Fitted the CT484746 and get the identical problem!

    The packaging was marked CT484746, the module itself was marked CT32M64S4W7E.16FG PC133.

    I note this is almost identical to the first module CT32M64S4W8E.16FG PC100.

    For reference, the original OEM memory was marked M464S3254BT2-L75 PC133.

    All three memory modules work fine on their own. I've tried all the permutations of two memory modules in the two slots. Whenever the second slot is populated, the fault occurs: Operating System Not Found when booting off the HD, but by booting off a bootable CD and using the the CD's boot loader to boot off the HD it comes up fine.

    The Dell hardware diagnostic shows no faults.

    I don't see anything to indicate whether the memoy modules are EDO or Fast Page, and I can't see which type the PC expects either. It's been suggested that the 'E' at the end of the part number indicates EDO and that sounds credible. Based on the results so far I suspect that all the memory modules are identical and compatible with the PC which must therefore be using EDO.

    So, I'm completely stumped. Any ideas what the heck is going on?

  13. #13
    Registered User geoscomp's Avatar
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    OK..the oem module is PC133....the replacement modules should be PC133 as well.
    BTW, fastpage and edo are old memory configurations, that refer to memory made starting in 1987 (fastpage) and memory starting in 1995 (EDO) and had to do with the read cycle between the memory and the cpu. They were replaced with current SDRAM in which there is a clock to allow for read/write timing.
    Your OEM module is a standard SODIMM PC133 module with CL3
    The replacement pc133 module is CL2
    The original module that you bought is PC100
    Oddly, there were 6 models of the 2500, and all say they used PC100 SODIMMS with a 32x64 chip configuration, with the newest three using a 16ns clock cycle. I would suspect that your second memory slot is defective, not the memory you are trying.
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  14. #14
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    Have you reset the bios, there should be a place in the bios to select the device the computer boots from.
    It seems with the addition of the 2nd memory module the bios has changed and needs to be setup and saved to boot from the proper device.

  15. #15
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    Quote Originally Posted by geoscomp
    I would suspect that your second memory slot is defective, not the memory you are trying.
    That would certainly explain why all the modules seem fine in slot A and they all produce this problem in slot B. But it is curious that the Dell memory diagnostic doesn't show any errors, and also that the system works fine once it has booted. It just seems that for some peculiar reason, booting with 512MB of RAM installed does something nasty to the MBR. I just have no idea why!

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