mb supports double-sided yet detects only half RAM

Discussion in 'Asus' started by SN, Apr 17, 2004.

  1. SN

    SN Guest

    I know this is an outdated config, but it will be great if you could

    I'm trying to upgrade RAM on an assembled Pentium3 PC 1.1Ghz
    Existing SDRAM was 128, I am trying to add another 256 but it detects
    only 128 of the new 256

    Motherboard M6TWG V2.0 - manual says it supports double sided SDRAM
    with max board capacity of 512MB

    The motherboard manual states:
    DIMM memory bus frequency always run 100MHz, if you use SRAM PC 133

    SDRAM HY57V28420AT-S , 256MB SDRAM, PC133, double sided
    Config 1. BIOS POST only reports half the memory (128MB) when booting
    up with single 256MB module

    Config 2. BIOS POST only reports 256MB memory when booting up with
    256MB module plus older 128MB module (same vendor, PC133)
    With Config 2...
    Windows 2000 System Infomation --> Hardware --> Memory reports

    System Information report written at: 04/17/2004 09:48:23 PM

    Range Device Status
    0xCC000-0xCFFFF System board OK
    0xF0000-0xF7FFF System board OK
    0xF8000-0xFBFFF System board OK
    0xFC000-0xFFFFF System board OK
    0xFEF0000-0xFEFFFFF System board OK
    0x0000-0x9FFFF System board OK
    0x100000-0xFEEFFFF System board OK
    0xFEE00000-0xFEE00FFF System board OK
    0xFFB00000-0xFFB7FFFF System board OK
    0xFFF00000-0xFFFFFFFF System board OK
    0xE0000-0xEFFFF System board OK
    0xA0000-0xBFFFF PCI bus OK
    0xA0000-0xBFFFF Intel Corporation 810 Graphics Controller Hub OK
    0xC0000-0xDFFFF PCI bus OK
    0xFF00000-0xFFEFFFFF PCI bus OK
    0xD0000000-0xD3FFFFFF Intel Corporation 810 Graphics Controller Hub OK
    0xD6000000-0xD607FFFF Intel Corporation 810 Graphics Controller Hub OK
    0xD5000000-0xD50000FF Realtek RTL8139(A) PCI Fast Ethernet Adapter OK

    With Config 2...
    Windows 2000 System Infomation --> Hardware --> IRQs

    System Information report written at: 04/17/2004 09:51:04 PM

    IRQ Number Device
    9 Microsoft ACPI-Compliant System
    11 Realtek RTL8139(A) PCI Fast Ethernet Adapter
    11 Intel(r) 82801AA USB Universal Host Controller
    11 Intel(r) 82801AA SMBus Controller
    11 AC'97 Driver for Intel(r) 82801AA Controller
    14 Primary IDE Channel
    15 Secondary IDE Channel
    8 System CMOS/real time clock
    13 Numeric data processor
    6 Standard floppy disk controller
    4 Communications Port (COM1)
    12 PS/2 Compatible Mouse
    1 Standard 101/102-Key or Microsoft Natural PS/2 Keyboard
    10 MPU-401 Compatible MIDI Device

    SN, Apr 17, 2004
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  2. Apparently a Biostar (i.e. not Asus) board with i810 or somesuch.
    This memory chip is one of the 32Mx4 variant, which neither the i810 nor
    the i440BX or i815 can address fully - you'd need a VIA 694X for that.
    (BTW, electrically the module has only one "side" or rather bank with 16
    * 4 = 64 bits width.) For this board you'd need a module with 16 chips
    of 16Mx8 each, the kind that also works in BX boards.

    Stephan Grossklass, Apr 17, 2004
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  3. SN

    Paul Guest

    Org. Part Number Density Refresh Voltage Speed PKG
    32Mx4 HY57V28420HCLT 128M 4K 3.3V 6/K/H/8/P/S 54 TSOP
    32Mx4 HY57V28420HCT 128M 4K 3.3V 6/K/H/8/P/S 54 TSOP

    (Same datasheet for both chips - The "L" is presumably low power.)

    Banks of memory are 64bits wide. On your DIMM, it takes all
    16 chips, each of which is 4 bits wide, to make a bank. So,
    even though the DIMM is "double sided", there is still only
    a single bank of memory.

    One of the differences between 32Mx4 and 16Mx8, is that the
    second of the two needs one fewer address bit, to select a
    location in memory. If a Northbridge is missing that address
    bit, one of the symptoms is that only half the memory shows

    See page 42 of the following doc (the last entry in the table)
    for the largest valid DIMM configuration. It shows as
    (16) 16Mx8 chips. This is the datasheet for "82810-DC100 GMCH":

    Your motherboard is actually a Biostar motherboard, and not made
    by Asus. (The nearest Asus equivalent might be the MEW-AM,
    not sure.) This Crucial page lists memory guaranteed to work
    for a M6TWG:


    What is funny is, the fastest of the memory is also the cheapest
    on that page, so return the DIMM you've got and spend $90 on
    a stick of the good stuff.

    Paul, Apr 17, 2004
  4. SN

    SN Guest

    I wish the motherboard manual had included this little nugget of
    compatibility information.

    Thanks a lot Paul for your time and detailed explanation.
    Thanks to you too Stephan.

    SN, Apr 18, 2004
  5. SN

    daytripper Guest

    Your motherboard was built - and the manual written - before the incompatible
    dimms were being produced...

    daytripper, Apr 18, 2004
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