Motherboard does not see all my RAM

By monkeemanboy
Jan 3, 2006
  1. I have a TYAN S2875 dual opteron (275) motherboard and have recently purchased 4 x 2 Gb of DDR400 PC3200 ECC registered memory modules (8Gb in total). These are matched pairs, in dual channel configuration and are on the approved vendor list. I have tested each stick and each one works fine and shows its full capacity. However when all sticks are inserted, system properties only shows 3.43Gb!! (should be just less than 8). Even when 2 sticks are taken out leaving 4Gb left, the system properties still only show a maximum of 3.43Gb available!!

    Is there an option in the Bios that I need to activate or something else I'm not doing correctly?

    I'm running Windows XP Pro SP2 and mobo bios is all up to date.

    Any Ideas? :confused:
  2. howard_hopkinso

    howard_hopkinso TS Rookie Posts: 24,177   +19

    Hello and welcome to Techspot.

    2.29 – Installing the Memory
    Before attempting to install any memory, make sure that the memory you have is
    compatible with the motherboard as well as the processor.
    The following diagram shows common types of DDR SDRAM modules:
    Here are a few key points to note before installing memory into your Tiger K8W:
    • Always install memory beginning with DIMM1
    • AMD OpteronTM processors support 64bit (non-interleaved) or 128bit
    (interleaved) memory configurations
    • At least ONE Registered DDR SDRAM module must be installed for the
    system to turn on and POST (power on self test)
    • 128MB, 256MB, 512MB, 1GB, and 2GB* Registered ECC/non-ECC
    PC3200**/PC2700/PC2100/PC1600 DDR SDRAM memory modules are
    • All installed memory will be automatically detected
    • The Tiger K8W supports up to 8GB.*
    * Not validated at the time of print; subject to change.
    ** With Opteron 246 C-stepping CPU and above
    This chart outlines the rules for populating memory
    (Note: X indicates a populated DIMM Slot)
    DIMM Slot 128-Bit Support 64-Bit Support
    DIMM1 X X X X
    DIMM2 X X
    DIMM3 X X X X
    DIMM4 X X

    This is taken from your mobo manual. Note where it says • The Tiger K8W supports up to 8GB.*

    * Not validated at the time of print; subject to change.

    It might be a good idea to contact Tyan, and see what they say about installing 8gigs of ram.

    Regards Howard :wave: :wave:
  3. Justin

    Justin TS Rookie Posts: 942

    Well, for one, Windows XP does not support that much memory. From

    Unless you start using Windows XP 64bit or Linux, you're not going to be able to use that RAM.
  4. AJ9027

    AJ9027 TS Rookie

    Ram Problem

    The first thing that I would check in this situation is that your motherboard can support 8 Gbs of ram. Also try to update your OS. I had a problem very similar to yours before when I was using Windows XP PRO SP2 and I reverted to SP1 and it worked perfectly. Hope this was helpful to you.
  5. monkeemanboy

    monkeemanboy TS Rookie Topic Starter

    arh hah

    Thanks everyone for your suggestions. After looking on the microsoft website it does indeed seem to be a limitation of the 32-bit XP pro version. Will be upgrading to the x64 soon me thinks. Interesting that it might might be solved by reverting back to SP1 though.

    Quote from

    "Description of Windows XP Professional x64 Edition
    Windows XP Professional x64 Edition is a near feature-complete version of Windows XP Professional that runs on x64 processors. Windows XP Professional x64 Edition supports 128 GB of RAM and 16 terabytes of virtual memory address space, as compared to 4 GB of both physical RAM and virtual memory address space for 32-bit Windows XP Professional."
  6. Justin

    Justin TS Rookie Posts: 942

    As I stated, it's a limitation of the 32bit environment XP provides. Your only choice is to go with the server versions of Windows or switch to x64. 32bit-version, SP1 or no, can't utilize that much ram.

    Of course, with a need for that much RAM, I wonder why you are using Windows XP Pro in the first place. What's your particular application for such a beefy amount of memory?
  7. rockzz

    rockzz TS Rookie

    maybe i can help

    hey man maybe you need to put your memory tight or clean the edge of your memory with an eraser.. sometimes the motherboard cannot detect the memory if it is loose... or maybe the memory is not compatible with motherboard
  8. howard_hopkinso

    howard_hopkinso TS Rookie Posts: 24,177   +19

    Of course, Soul Harvester is absolutely correct.

    I wish I`d thought of that Doh.

    Regards Howard :blush:
  9. monkeemanboy

    monkeemanboy TS Rookie Topic Starter

    yep indeedy

    In response to "Soul Harvester"

    Applications I'm running are 3D modelling/animation and SFX software. With the recent move to HD TV compositing and extremely high print resolutions. The rendering engines need high amounts of ram to sort the arrays and of course higher processing power speeds up the process as well. I'm still getting ram refusals (with 4GB) on some high poly scenes so hopefully 8GB on a windows x64 should do the trick. Does anyone know if the other operating systems on the market would be better suited for my work?
  10. Jaquio

    Jaquio TS Rookie Posts: 26

    how bout MAC?
  11. monkeemanboy

    monkeemanboy TS Rookie Topic Starter

    errr no!

    I have a mac myself which I love dearly ...but not for my 3D applications!!

    They are unfortunateley well known to be a bit crud in that department. Take a look at some of the benchmark tests. The latest G5 quad is a good attempt but it still falls way short of rendering times from AMD opterons. My latest machine is a quad opteron with 2 x dual core 64 bit processors, 16 Gigabites of Ram and a PNY quadroFX3000. The ability to build your own machine to these kind of specifications is what makes them piss all over the "off the shelf" desktops ...including macs. No offence but no thanks!

    This might change soon however with the switch to Intel ...heres hoping!
  12. Jaquio

    Jaquio TS Rookie Posts: 26

    oh... i see... didnt know that :D
  13. AJ9027

    AJ9027 TS Rookie

    Windows XP X64

    Windows XP x64 would definatley be the best OS for an AMD Athlon 64 preocessor because it uses it to its full 64-bit potential. Glad I could contribute.
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