4 x DDR = Slower?

Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

I just updated my old p4 3ghz with MSI 875P chipset from 1 to 2gb of
memory. it had 2x512mb (PC3200 cas2) corsair twinx. now it has 4 of them.

suddenly the BIOS reports the memory speed as 266 (133 DDR) instead of
400DDR (200DDR).

take any of the two sets and its back to 400 again.

anyone know why this would happen?

Paul
6 answers Last reply
More about slower
  1. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    On Sun, 28 Aug 2005 17:39:03 -0500, Paul Kelly <pkelly@virtual.org.uk> wrote:

    >I just updated my old p4 3ghz with MSI 875P chipset from 1 to 2gb of
    >memory. it had 2x512mb (PC3200 cas2) corsair twinx. now it has 4 of them.
    >
    >suddenly the BIOS reports the memory speed as 266 (133 DDR) instead of
    >400DDR (200DDR).
    >
    >take any of the two sets and its back to 400 again.
    >
    >anyone know why this would happen?
    >
    >Paul

    Because the memory buses can't make timing at 400mhz with more than two dimms
    installed...
  2. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    daytripper <day_trippr@REMOVEyahoo.com> wrote in
    news:j5i4h1tori2ufojl5t2qksm4o6054u1gbk@4ax.com:

    > On Sun, 28 Aug 2005 17:39:03 -0500, Paul Kelly <pkelly@virtual.org.uk>
    > wrote:
    >
    > Because the memory buses can't make timing at 400mhz with more than
    > two dimms installed...

    looks that way :(
  3. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    "" wrote:
    > I just updated my old p4 3ghz with MSI 875P chipset from 1 to
    > 2gb of
    > memory. it had 2x512mb (PC3200 cas2) corsair twinx. now it has
    > 4 of them.
    >
    > suddenly the BIOS reports the memory speed as 266 (133 DDR)
    > instead of
    > 400DDR (200DDR).
    >
    > take any of the two sets and its back to 400 again.
    >
    > anyone know why this would happen?
    >
    > Paul

    You are not on your own with this issue. It makes me ask why these
    companies bother making the motherboard with 4 DIMM slots in the first
    place?

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  4. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    On Sun, 28 Aug 2005 21:27:48 -0500, Paul Kelly <pkelly@virtual.org.uk>
    wrote:

    >daytripper <day_trippr@REMOVEyahoo.com> wrote in
    >news:j5i4h1tori2ufojl5t2qksm4o6054u1gbk@4ax.com:
    >
    >> On Sun, 28 Aug 2005 17:39:03 -0500, Paul Kelly <pkelly@virtual.org.uk>
    >> wrote:
    >>
    >> Because the memory buses can't make timing at 400mhz with more than
    >> two dimms installed...
    >
    >looks that way :(

    Are those double sided DIMMs... i.e. you now have 4 ranks of memory on each
    channel? Have you tried setting the timings and speed manually in BIOS
    Setup: raise the CAS latency & other timings by a clock tick and then raise
    the clock rate? Sometimes that'll work. I always advise people to get
    single sided DIMMs now to help avoid bus load problems, such as those:
    http://www.newegg.com/Product/Product.asp?Item=N82E16820146541

    --
    Rgds, George Macdonald
  5. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    George Macdonald <fammacd=!SPAM^nothanks@tellurian.com> wrote in
    news:9516h1lhodc74dleflea3i230qu0lgkgkl@4ax.com:


    >I always
    > advise people to get single sided DIMMs now to help avoid bus load
    > problems, such as those:
    > http://www.newegg.com/Product/Product.asp?Item=N82E16820146541

    I tried disabling SPD and setting 2-3-3-6, all boots ok but still 266.
    this is a dump of my memory spd.

    new ram : 200mhz = 2-3-2-6
    old ram : 200mhz = 3-3-3-8

    maybe this mix has forced the pc into some sort of compromise. i dont
    know much about CAS/RAS Precharges. I had to look up the meaning of SPD

    I think the answer would be sell the memory and stick to two 1gb modules
    but its not really worth it on a 2 year old pc. think ill just wander in
    the slow lane until those nice AMD socket 1207 board show up:)

    Paul

    Memory SPD
    ---------------------------------------------------------------------

    DIMM #1

    General
    Memory type DDR-SDRAM
    Manufacturer (ID) Corsair (7F7F9E0000000000)
    Size 512 MBytes
    Max bandwidth PC3200 (200 MHz)
    Part number CMX512-3200C2
    Manufacturing date Week 00/Year 00

    Attributes
    Number of banks 2
    Data width 64 bits
    Correction None
    Registered no
    Buffered no

    Timings table
    Frequency (MHz) 133 166 200
    CAS# 2.0 2.5 3.0
    RAS# to CAS# delay 2 3 3
    RAS# Precharge 2 3 3
    TRAS# 6 7 8


    DIMM #2

    General
    Memory type DDR-SDRAM
    Manufacturer (ID) Corsair (7F7F9E0000000000)
    Size 512 MBytes
    Max bandwidth PC3200 (200 MHz)
    Part number CMX512-3200LL
    Manufacturing date Week 00/Year 00

    Attributes
    Number of banks 2
    Data width 64 bits
    Correction None
    Registered no
    Buffered no

    Timings table
    Frequency (MHz) 200
    CAS# 2.0
    RAS# to CAS# delay 3
    RAS# Precharge 2
    TRAS# 6


    DIMM #3

    General
    Memory type DDR-SDRAM
    Manufacturer (ID) Corsair (7F7F9E0000000000)
    Size 512 MBytes
    Max bandwidth PC3200 (200 MHz)
    Part number CMX512-3200C2
    Manufacturing date Week 00/Year 00

    Attributes
    Number of banks 2
    Data width 64 bits
    Correction None
    Registered no
    Buffered no

    Timings table
    Frequency (MHz) 133 166 200
    CAS# 2.0 2.5 3.0
    RAS# to CAS# delay 2 3 3
    RAS# Precharge 2 3 3
    TRAS# 6 7 8


    DIMM #4

    General
    Memory type DDR-SDRAM
    Manufacturer (ID) Corsair (7F7F9E0000000000)
    Size 512 MBytes
    Max bandwidth PC3200 (200 MHz)
    Part number CMX512-3200LL
    Manufacturing date Week 00/Year 00

    Attributes
    Number of banks 2
    Data width 64 bits
    Correction None
    Registered no
    Buffered no

    Timings table
    Frequency (MHz) 200
    CAS# 2.0
    RAS# to CAS# delay 3
    RAS# Precharge 2
    TRAS# 6
  6. Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

    On Mon, 29 Aug 2005 17:34:24 -0500, Paul Kelly <pkelly@virtual.org.uk>
    wrote:

    >George Macdonald <fammacd=!SPAM^nothanks@tellurian.com> wrote in
    >news:9516h1lhodc74dleflea3i230qu0lgkgkl@4ax.com:
    >
    >
    >>I always
    >> advise people to get single sided DIMMs now to help avoid bus load
    >> problems, such as those:
    >> http://www.newegg.com/Product/Product.asp?Item=N82E16820146541
    >
    >I tried disabling SPD and setting 2-3-3-6, all boots ok but still 266.
    >this is a dump of my memory spd.
    >
    >new ram : 200mhz = 2-3-2-6
    >old ram : 200mhz = 3-3-3-8
    >
    >maybe this mix has forced the pc into some sort of compromise. i dont
    >know much about CAS/RAS Precharges. I had to look up the meaning of SPD

    Sometimes BIOS auto-settings just don't get it right. I'd say 2-3-3-6 is
    way too ambitious here to get all 4 DIMMs working at DDR400; in fact there
    are not many modules around which work at CASL=2 in any system. I'd start
    with 3-3-3-8 and maybe even slower than that (3-4-4-10) and if possible
    tighten back up when you get it working.

    --
    Rgds, George Macdonald
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