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Anyone up for some tREF discussion?

Discussion in 'Memory' started by Jimbo Mahoney, 7 May 2006.

  1. Jimbo Mahoney

    Soldato

    Joined: 18 Oct 2002

    Posts: 6,294

    Been playing around with tREF on my system in sig.

    With the memory @ 250 Mhz @ 2-2-2, 1T, 200 divider, I got the following graph:

    EDIT - Yellow line shows 2GB OCZ @ 213 Mhz.

    [​IMG]

    As you can see, a clear relationship between tREF and errors, and a slight reduction in bandwidth @ low tREFs.

    My questions are:

    Is the ideal tREF specific to the RAM?
    Is it specific to the memclock?
    Is it specific to the divider?

    From previous discussions, I'm quite a fan of the following:

    ideal tREF = refresh rate / (1/clockspeed)

    The problem is that there is so much mis-information about tREF about, and that table showing tREFs grouped into refresh rates (3.9, 7.8, 15.6 us) and clockspeeds (100 - 200 Mhz) only confuses things. Don't even get me started on Dracula's tREF tables . :confused:

    Does anyone have any simple theory on tREF?

    At least Dracula's four best and four worst tREFs bear some resemblance to my findings:

    Four best =

    * 1560
    * 3072
    * 3120
    * 4708

    Four worst =

    * 0016
    * 0032
    * 0064
    * 0128


    My four best (1GB BH5) =

    * 3684
    * 3072
    * 4708
    * 4196

    EDIT - My four best (2GB OCZ) =

    * 2336
    * 2048
    * 2560
    * 1536

    I can only assume higher tREF = better, but knowing that the memory must be refreshed to keep the data 'alive', a higher tREF could also result in data loss...
     
    Last edited: 13 May 2006
  2. Jimbo Mahoney

    Soldato

    Joined: 18 Oct 2002

    Posts: 6,294

    Looking astaris' post here:

    http://www.dfi-street.com/forum/showpost.php?p=139338&postcount=27

    It seems that my best tREFs all fall in his 1.95us category.

    Namely:

    1,95 us
    1536= 100mhz -> 195 Mem Clock cycles
    2048= 133mhz -> 259
    2560= 166mhz -> 324
    3072= 200mhz -> 390

    1.95 us
    3684= 120mhz -> 234
    4196= 140mhz -> 273
    4708= 150mhz -> 292
     
  3. Minstadave

    Caporegime

    Joined: 8 Jan 2004

    Posts: 27,772

    Location: Rutland

    Wow, nice work mate, I'll make sense of it in the morning, but looks like you've been working hard on this :)
     
  4. Jimbo Mahoney

    Soldato

    Joined: 18 Oct 2002

    Posts: 6,294

    I was bored after having to RMA my new 2GB RAM, so I thought a hungover day of tinkering with BIOS settings and running memtest while listening to music and snacking would be just what the doctor ordered :D
     
  5. Firegod

    Sgarrista

    Joined: 12 Sep 2003

    Posts: 8,816

    Location: Newcastle, UK

    Ahhh yes, we've all been there before. :p
     
  6. Jimbo Mahoney

    Soldato

    Joined: 18 Oct 2002

    Posts: 6,294

    Updated with a yellow line for my 2GB OCZ set.