memory - Is there an explanation, why my computer only works with this RAM configuration?

05
2014-04
  • openscript.ch

    Recently I had a problem with my desktop computer, which was working fine over the last 3 years. The hardware has the following specification:

    • Motherboard: ZOTAC GeForce 9300-ITX [GF9300-I-E]
      • Onboard NVidia graphics (shared RAM)
    • CPU: Intel Core2Duo E5300
    • RAM: GEIL PC2-6400 DDR2-800 C5 GREEN DUAL CHANNEL 2x2GB

    The problem was that after I pressed the start button I heard the HDD spinning up and the fans went on, but black screen, no beeps, and any other reaction of the system.

    So I pulled out one of the RAM bars, let's say R1 from slot S1. After a CMOS reset the system booted up. R1 again in the S1 caused the same problem. Somehow I came up with the idea to put the R2 into S1 and R1 into S2. Now the strange thing. The machine works fine now! I ran memtest84 without any errors! The problem is still reproducible.

    Has anyone an idea how this can happen? Solar wind?

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    64 bit - Why does installing NVidia 9600GT graphics card, take 1GB of RAM away from Windows?
  • Nick G

    I've changed graphics cards in my PC and now Windows 7 (32bit) is reporting that I have a whole gigabyte less physical RAM in my PC. Why is this?

    Firstly, the machine has 4GB of physical RAM. The old card was an ATI 2600XT with 256MB and the new card is an NVidia 9600GT with 512MB.

    With the ATI card windows sees 3326MB. With the NVidia card, windows sees 2558MB.

    I realise that due to address space restrictions I will not see all 4GB with 32bit windows, but why is there such a massive loss of RAM when simply changing cards (bearing in mind BOTH cards have their own RAM and borrow no main memory like some built on chipsets do). Would using 64 bit windows solve this?


    • Related Answers
  • Eric J.

    Because it (probably) has 1GB of video memory, which has to be taken out of the 32 bit Vista 4GB address space.

    32 bit Windows has to share 4GB between physical memory and all of the memory mapped devices installed in the system. That's why you typically only have access to a bit more than 3GB of memory even with a lesser graphics card.

    If you move to 64-bit Windows, the address space is much larger so you won't run into that issue and will get your full installed RAM. One downside though is that programs will actually use more memory, mostly because the size of pointers is larger.

    EDIT:

    It doesn't matter that the card has it's own memory. You still need address space for it's memory to be mapped into. I just noticed in the post that it's a 512MB card not a 1GB card, so there may be something else at work beyond the delta of 256MB that you will lose from the address space for the increase in card memory.

  • kmarsh

    Check the BIOS and see if the memory reported there has changed.

    Then run memtest86+ from bootable media and see what that reports.

    If possible, put the old card in and see if any of these numbers change.

    Then, post the information here. This will help sort out whether it is a hardware, driver, or windows issue.

  • ta.speot.is

    This should help explain: http://blogs.technet.com/markrussinovich/archive/2008/07/21/3092070.aspx