RAM Timings - tRFC and tRC - whats the difference?

Discussion in 'Die-hard Overclocking & Case Modifications' started by BLEH!, Jun 17, 2011.

  1. BLEH!

    BLEH! Ancient Guru

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    Hey Gurus

    Maybe I'm being a little anal here but I'm doing what many of us do and trying to squeeze every last drop of performance out of my rig. Been faffing with RAM timings and some of the smaller numbers have me confused. I'm familiar with the normal 4 and can't seem to get any tighter where I am now (numbers to follow), but I'm wandering if faffing with any of the other timings with improve performance at all. Looking at CPU-Z though there's an odd thing, it might be a typo, I'm not sure, but I thought it work a check.

    Anyway, currently running Corsair Domi (3 x 2 GB) @ 1600 MHz @ 1.7 V. FSB 200 MHz, CPU 4.2 GHz, (x 21 multi), etc.
    Timings wise, under the "Memory" tab, this is whats confusing me, in comparison with the "SPD" tab. Highlighted the confusion in bold.
    My Memory from the "Memory" Tab:
    DRAM Freq: 800.0 MHz
    FSB:DRAM: 2:8
    CL: 7.0 clocks
    tRCD: 8 clocks
    tRP: 7 clocks
    tRAS: 20 clocks
    Row Refresh Cycle Time tRFC: 88 clocks
    CR: 1T

    and from the "SPD" Tab, XMP-1600 specs:
    Frequency: 800 MHz
    CAS# Latency: 7.0
    RAS# to CAS#: 8
    RAS# Precharge: 7
    tRAS: 20
    tRC:41
    Command Rate: 2T
    Voltage: 1.65

    I apologise for typing everything but I'm crap with HTML and have no idea how to embed pictures. So my main question is I guess, is tRFC and tRC the same and can I drop the 88 down to 41 in the BIOS for a performance boost?

    Either that or does anyone have any mad suggestions for improving performance by tweaking?

    Thanks

    BLEH!
     
  2. BLEH!

    BLEH! Ancient Guru

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    Anyone?
     
  3. Mufflore

    Mufflore Ancient Guru

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    Here you go, get the fix for your anal issues ;)
    http://www.anandtech.com/show/3851/...w-about-sdram-memory-but-were-afraid-to-ask/3

    Basically, memory contents must be refreshed or the data will disappear.
    This is done in banks of memory addresses.
    The time allowed to complete a refresh of a whole bank is tRFC.
    There is some safety margin to make sure that the job is finished so there may be room to tweak.

    This statement is key
    = from the start of a bank refresh, tRFC cycles are waited before it can be activated again.
     
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  4. BLEH!

    BLEH! Ancient Guru

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    Cool, thanks
     

  5. Messerschmitt

    Messerschmitt Master Guru

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    Hi. I'm coming with the same question. Unfortunately I did not really understood Mufflore explanation.

    Actually my question is the following:

    Should I match the tRFC to the tRC in the SPD table?
    So if it says tRC in SPD 33, can I set the tRFC to 33?
    If not, how can I find the value?
     
  6. TechFreaK

    TechFreaK Guest

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    ^
    Hi,

    its not the same, tRC is ram's internal timing.

    http://www.tweakers.fr/timings.html#tRC

    tRFC affects ram read speed, higher vale = lower read, stabler operation.

    Im at 1092mhz - tRFC 82 (default is 70 at 1066mhz or 52 at 800mhz). DDR3 has higher tRFC 90-120+


    You can check Aida64 > go to motherboard > chipset >> scroll below for advanced timings. btw those that are missing could be risky, memset 4.1 doesn't show tRC either.
     
    Last edited: May 13, 2012
  7. Messerschmitt

    Messerschmitt Master Guru

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    Thanks. So is there a way to tell which is the tRFC number my memory supports? Unfortunately the SPD in CPU-Z does not provide that information
     
  8. Horus-Anhur

    Horus-Anhur Ancient Guru

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    You can see that in the UEFI. Set the kit to default and it will set the JEDEC for that speed. Or set the XMP profile, and it will set the XMP value.
    But if it's the tuned value, the only way is trial and error. Just lower it until it starts producing errors.
     
  9. vestibule

    vestibule Ancient Guru

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    Its real difficult to beat XMP timings.
    As cine bench 20 will show you with its render scores.
     
  10. Horus-Anhur

    Horus-Anhur Ancient Guru

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    Cinebench scales very poorly with memory. It's a terrible benchmark for memory performance.
    Manual tight timings will beat XMP, by a decent margin.
     

  11. vestibule

    vestibule Ancient Guru

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    I will look into it again.
    he he. :)
     
  12. D1stRU3T0R

    D1stRU3T0R Master Guru

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    eyyo you necro'ed a 10+ year old topic :D
     
  13. vestibule

    vestibule Ancient Guru

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    I don't mean to take over this thread but I just messed around with my ram.
    So 3200 XMP cl16 score 98.6%default and the OC 3600 cl16 score 110%. So OC is a win then. :)
    3200.jpg
    3600.jpg
     
  14. Horus-Anhur

    Horus-Anhur Ancient Guru

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    Holy crap dude, what are you thinking using userbenchmark. That is the worst site in the whole internet for hardware comparisons.

    If you want to test your memory, you can use some of these programs.
    Aida64. Not the most accurate, but it's an easy way to benchmark memory bandwidth and latency.
    1usmus Membench. It runs a bunch of instances of memtest and gives the time to complete. Lower is better.
    Y-cuncher. Loves memory speed. Doesn't scale so well with memory timings.
    Super Pi. A classic for testing memory and IPC.
    Geekbench3. It has a decent test for memory.
    Linpack. It's a CPU throughput test, but scales well with memory speed and timings.
    Timespy CPU test. Also scales well with memory speeds.
     
  15. vestibule

    vestibule Ancient Guru

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    LOL. I thought it looked suspect, but seemed to be the only thing around the internet on search would provide and so I used that.
    I will try some of your stuff. TY for the heads up.
     

  16. vestibule

    vestibule Ancient Guru

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    OK here we go again with a snippet of 1usmus Membench. :)
    3200XMP
    B1.jpg
    3600 custom.
    B2.jpg
    Yep the OC wins. :)
     
  17. Horus-Anhur

    Horus-Anhur Ancient Guru

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    You can probably tighten some timings and get under 120s.
     
  18. bballfreak6

    bballfreak6 Ancient Guru

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    Just started tweaking the ram a bit too on my new 7700X build partly because my system can't run at its XMP speed of 6200MHz and I had to drop it down to 6000MHz so was hoping to squeeze a bit more out of it. It's using SK Hynix chips I so followed Buildzoid's secondary/tertiary timings video on Youtube (while keeping the primary timings as per XMP for now) and to my surprise it's actually made a noticeable difference to my frame rates in a couple of games I've tested. For example CP2077 on my setup it'll occasionally dip into mid 40's fps driving around the city but since the tweak it doesn't go below 50 fps now which is pretty cool (more surprised if anything as I wasn't really expecting to see much of a difference).
     
  19. vestibule

    vestibule Ancient Guru

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  20. bballfreak6

    bballfreak6 Ancient Guru

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