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Thread: 680i ram timing guide

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    680i ram timing guide

    Hi mates,

    I made a ram timing guide kinda like the "old DFI-street guide".
    The guide can be found at evga's forum, fell free to check it and comment.
    http://www.evga.com/community/messag...TOPIC_ID=32135

    I also made a Bios flash guide with bios collection, FAQ and OC-guide:
    http://www.evga.com/community/messag...TOPIC_ID=30071


    edit: copy/pasted the thread and redid the formatting


    Ram timing guide

    As you can imagine, this has taken a lot of testing. 40-something benchmarks actually [] On to the point..

    Each chipset (680i/975/965) acts differently to how timings are applied.
    Some of you are probably familiar with how DDR1 ram acted on timings - DDR2 acts a bit differently and some timings are less important than what they used to be.

    The EVGA 680i SLI board has an entire bios section dedicated to ram timings. So why not do some tweaking.
    The guide follows the bios order, skipping Command Per Clock which is saved for last.

    The section looks like this:



    I've tested all timings one by one. Sisoft Sandra 2007 was used for benchmarking. All the first benchmark results were discarded since they tend to fluctuate.

    My ram specs:
    2x1gb Corsair PC2-8500C5 (D9)
    Unlinked to 800mhz @ 2,175v
    In blue DIMMs, running dual chan.
    Base timings used: 5-4-4-12-(2T) / 3-23-5-9-(7,8)
    Base Sisoft score: Int: ~5580 / Float: ~5570


    tCL:
    Large influence on stability / Medium influence on bandwidth
    From CAS 5 to 4 results change ~5-10mb/s. The same change will most likely be seen when going to CAS 3.
    This timing is widely seen as most important (Command rate disregarded).
    Recommendation: 4 for normal usage, 5 when oc'ing. Tweaked: 3.


    tRCD:
    Medium influence on stability / Large influence on bandwidth
    tRCD going from 4 to 3 gives ~15mb/s. From 5 to 4 also yields 10-15mb/s.
    This timing is considered second important after CAS, but actually it's more important on 680i/DDR2.
    Recommendation: 4 for oc/normal usage. 5 if you want to push mhz. Tweaked: 3


    tRP:
    Medium/small influence on stability / Small influence on bandwidth
    Results vary close to nothing when changing from 3 to 4 to 5.
    Still this timing needs to finish its cycle before a new one starts, so dont set it higher than 5.
    Recommendation: 4 for oc/normal usage. 5 if you want to push mhz. Tweaked: 3


    tRAS:
    Small influence on stability / Small influence on bandwidth
    tRAS seems to act differently on integer/float results. Integer, going from 15 to 10 changes by ~5mb/s. Float doesnt change.
    tRAS is an "end-timing", so dont go to high. And not lower than what tCL+tRCD equals.
    Recommendation: 12 for oc/normal usage. 15 if you want to push mhz. Tweaked: 8


    tRRD:
    Small influence on stability / Small influence on bandwidth
    tRRD of 2 didnt change the results. Nor did a tRRD of 4. This is a delay-timing so a too low value may result in recalculation.
    Recommendation: Auto for oc/normal usage. 4 if you want to push mhz. Tweaked: 2


    tRC:
    Medium influence on stability / Large influence on bandwidth
    This timing is quite surprising. Going from 30 to 21 gave ~90mb/s. From 23 to 21 gave ~15-20mb/s.
    tRC is last timing before ram burst (data transfer).
    Dont set too high. And tRC should be greater than tRAS + tRP or you might get corruption.
    Recommendation: 21 for normal usage. 30 if you want to push mhz. Tweaked: 15


    tWR:
    Small influence on stability / Small influence on bandwidth
    Small change from 6 to 3. Setting timing too low will cause ram to fail switching to "read mode".
    Recommendation: Auto for oc/normal usage. 6 if you want to push mhz. Tweaked: 3


    tWTR:
    Large influence on stability / Small influence on bandwidth
    From 10 to 8 didnt change results. 6 would lock up the system. This timing gives no bonus but affects stability a lot. Use with care.
    Recommendation: Auto for oc/normal usage. 10 if you want to push mhz. Tweaked: 8(7)

    tREF:
    Small influence on stability / Small influence on bandwidth
    Changing to 3,9us didnt show improvements in benchmark. It also didnt seem to affect stability. tREF was important with DDR1.
    Recommendation: Auto for oc/normal usage. 7,8us if you want to push mhz. Tweaked: 3,9us


    Command Rate:
    Settings are 2T/1T. You probably already know a lot about this timing.
    The 680i struggles running 1T above 800mhz. So do the ram - atleast 2,2v are needed.
    This timing gives a great boost to bandwidth, but is fairly hard to attain.
    I wont recommend any setting regarding this timing. You need to find what mhz you get with 1T, then find mhz with 2T, then compare benchmarks.


    Post words:
    The tRC and tRCD are two timings to take notice of. They yield good results compared to how they affect stability.
    CAS isnt as important as in the DDR1 days. You might even say timings in generel arent as important as with DDR1.

    To read more on the technical aspect of DDR2 go here:
    http://www.digit-life.com/articles2/...ddr2-rmma.html

    If you feel like messing with timings from Windows, try this tool:
    http://peecee.dk/uploads/0307/memset-3.2.zip
    Note: CAS(tCL) timing cannot be changed.

    Feel free to add/correct me if you have anything..

    Happy tweaking! []
    Last edited by illuminati-hwt; 04-16-2007 at 12:33 PM.
    Intel i5 2500K | Asus P8P67 Pro | EVGA 570 SC | ST75ZF 750W

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