CAS vs. Speed

Whats more favorable for ram that is going to be overclocked..

Memory with low CAS latency and lower speed or memory with higher CAS but higher speed..

Basically if i had two sets of 6gb Ram (or any equal amount of ram) and one set was ddr3 1600 6-8-6-20 vs ddr3 2000 9-9-9-24..which one would you prefer and why. what added benefits does lower cas latency have over higher speed and vice versa?
23 answers Last reply
More about speed
  1. There's tons of threads about this topic, I've authored too many to count.

    The 'Best' is High Frequency + Low-Tight CAS + Quality IC

    On the current P67's the ideal is 1600 MHz CAS 9 {9-9-9-24-2T} @ 1.50v; I too like the CAS 8 {8-8-8-24-2T} but it adds very little. Nice Article -> http://www.bit-tech.net/hardware/memory/2011/01/11/the-best-memory-for-sandy-bridge/1

    On the X58 by the 6GB reference, look at the Corsair Dominator TR3X6G1600C8D 1600MHz 8-8-8-24-2T ; they can be easily OC to 1800 MHz 8-8-8-24-2T and in doing so beat most of the comparable RAM and a negligible difference to the GT.

    Comparison Module #1: Mushkin Redline 996805 6-8-6-24 1600MHz
    Comparison Module #2: G.Skill Pi Series 7-8-7-24 1600MHz
    Comparison Module #3: Mushkin 998687 8-9-8-24 1866MHz
    Comparison Module #4: Corsair Dominator TR3X6G1600C8D 8-8-8-24 1600MHz
    Comparison Module #5: Kingston HyperX T1 9-9-9-27 1600MHz
    Comparison Module #6: Mushkin Blackline 998677B 7-7-7-20 1333MHz
    Comparison Module #7: Patriot Viper II Sector 7 9-9-9-27 1800MHz

    OC:

  2. well right now im using mushkin 6gb ddr3 1600 9-9-9-24 and im lookin at the g.skill pi 6gb ddr3 1600 6-8-6-20...does this upgrade make sense performance and financial wise?
  3. No, I would not mix match those kits. Mixing yields the worst and not the best or even a blending a/k/a middle ground.

    1600 9-9-9-24
    1600 6-8-6-20
    ===========
    1600 9-9-9-24 ; All 2 kits.
  4. no i was going to get rid of the 9-9-9-24..i wasnt going to add the 6-8-6-20. theyre going to replace the ram i have now
  5. If you're replacing a 6GB for another 6GB because of CAS 9-9-9-24 vs 6-8-6-20 then that's a waste of money.

    Instead, try OC the RAM above spec you've got nothing to loose:
    1600 9-9-9-24 ==> 1800 9-9-9-24-2T
    1600 9-9-9-24 ==> 1600 8-8-8-24-2T

    If it becomes unstable then either/both raise the DRAM Voltage +0.05v~+0.10v ; QPI/DRAM Voltage {IMC voltage} 1.25v~1.30~1.35v.

    Next, benchmark with Super PI and test with Memtest86+ w/4-passes.

    Good Luck! :)
  6. To be honest I cant even to get them to run at stock settings. I set voltage to 1.6 timings to 9-9-9-24 and freq to 1600 and it was unstable. So I set just the frequency back to auto and left the other settings and it's pretty stable. (even though my computer is still only seeing 4gb of the 6gb) could my qpi/dram voltage being on auto be the issue? I'm goin to pull some ram and see if I have a defective stick or something...
  7. Assuming they're in the correct DIMM Slots, see blow, then try cleaning the DIMM Slots. Unplug, use Isopropyl alcohol, dampen the RAM contacts, place them in the DIMM slots, pull out wipe/dampen and repeat, clean the RAM contacts and allow to dry 5 minutes prior to reinstalling.

    Q - What MOBO??

    I've been assuming an X58 MOBO because of the Triple channel kits...

    X58 DIMM Slots:
  8. If they're in the orange DIMM slots at defaults they 'should' have no problems running.

    Bizzare, most X58's don't require OC for 1600 MHz:
    6 x DIMM, Max. 24 GB, DDR3 2000(O.C.)*/1866(O.C.)*/1800(O.C.)*/1600(O.C.)/1333/1066 Memory

    Three approaches:

    RAM 1600 1600 6-8-6-20 ; often these timings are obtainable so in the example will be 8-8-8-24-2T

    [1] AI OC Tuner -> Auto
    DRAM Frequency - > DDR3-1600 MHz
    DRAM Voltage -> 1.65~1.70v
    DRAM Timing Control -> Manual
    timings 8-8-8-24
    -
    DRAM Timing Mode -> 2N

    [2] AI OC Tuner -> XMP
    DRAM Voltage -> 1.65~1.70v

    [3] AI OC Tuner -> DOCP
    DRAM Frequency - > DDR3-1600 MHz
    DRAM Voltage -> 1.65~1.70v
    DRAM Timing Control -> Manual
    timings 8-8-8-24
    -
    DRAM Timing Mode -> 2N
  9. Ok thanks. I'll give those a shot after I clean my ram slots as you suggested. Also, my ram is rated for 1.5-1.6v. Should I still try those higher voltage settings?
  10. Ooopsy, I did the above for the G.SKILL. The 1.50 is at SPD and the 1.60 is at Rated Frequency.

    Three UPDATED approaches:

    RAM 1600 1600 9-9-9-24-2T @ 1.60v

    [1] AI OC Tuner -> Auto
    DRAM Frequency - > DDR3-1600 MHz
    DRAM Voltage -> 1.60~1.65v
    DRAM Timing Control -> Manual
    timings 9-9-9-24
    -
    DRAM Timing Mode -> 2N

    [2] AI OC Tuner -> XMP
    DRAM Voltage -> 1.60~1.65v

    [3] AI OC Tuner -> DOCP
    DRAM Frequency - > DDR3-1600 MHz
    DRAM Voltage -> 1.60~1.65v
    DRAM Timing Control -> Manual
    timings 9-9-9-24
    -
    DRAM Timing Mode -> 2N
  11. ok ill give those a shot...i actually found my original post about this on the mushkin forum.. heres the link if you want to see what i did. looks like i use to know much more about this stuff than i do now lol..

    http://mushkingames.com/phpbb2/viewtopic.php?f=3&t=13545&sid=483acc5f1eabf367f78fd6639891d4e2

    im pretty hesitant to throw all those settings back on so im going to start with cleaning out the ram and take it one step at a time..
  12. You specs threw my for a loop, most X58 don't list "1600(OC)"; normally I'd suggest the following on 'most' ASUS X58's:

    [1] Easy - but might Post fail or BSOD {XMP RAM: 3 sticks no problem, 6 sticks can be an issue}:
    Ai Overclock Tuner [X.M.P.]

    yeah it's that easy...

    [2] Manual Speed with Auto Timings:
    Ai Overclock Tuner [Auto]
    DRAM Frequency -> [DDR3-1600 MHz]

    [3] Full Manual:
    Ai Overclock Tuner [Manual]
    DRAM Frequency -> [DDR3-1600 MHz]
    DRAM Timing Control /Enter

    DRAM CAS# Latency [9]
    DRAM RAS# to CAS# Delay [9]
    DRAM RAS# PRE Time [9]
    DRAM RAS# ACT Time [24]
    -
    DRAM Timing Mode [2N]
    ---
    DRAM Bus Voltage [1.60~1.65v] ± use closest value available ; per Rated spec voltage

    Increasing either the BCLK or QPI/DRAM Voltage {CPU IMC} is typically unnecessary with X58 + i7 9XX. The calculation for QPI/DRAM Voltage = DRAM Bus Voltage - 0.3v {±0.05v} and then only if you're having a failure.
  13. italianxmna89 said:
    Whats more favorable for ram that is going to be overclocked..

    Memory with low CAS latency and lower speed or memory with higher CAS but higher speed..

    Basically if i had two sets of 6gb Ram (or any equal amount of ram) and one set was ddr3 1600 6-8-6-20 vs ddr3 2000 9-9-9-24..which one would you prefer and why. what added benefits does lower cas latency have over higher speed and vice versa?

    I don't know the technical reasons, but generally the higher frequency will significantly out-perform. Also by underclocking the frequency you can tighten timings and benchmark it against each other, whereas you can't always do it the other way around (depending on the RAM).

    So my advice would be to go with the higher freq RAM.
  14. jaquith said:
    You specs threw my for a loop, most X58 don't list "1600(OC)"; normally I'd suggest the following on 'most' ASUS X58's:

    [1] Easy - but might Post fail or BSOD {XMP RAM: 3 sticks no problem, 6 sticks can be an issue}:
    Ai Overclock Tuner [X.M.P.]

    yeah it's that easy...

    [2] Manual Speed with Auto Timings:
    Ai Overclock Tuner [Auto]
    DRAM Frequency -> [DDR3-1600 MHz]

    [3] Full Manual:
    Ai Overclock Tuner [Manual]
    DRAM Frequency -> [DDR3-1600 MHz]
    DRAM Timing Control /Enter

    DRAM CAS# Latency [9]
    DRAM RAS# to CAS# Delay [9]
    DRAM RAS# PRE Time [9]
    DRAM RAS# ACT Time [24]
    -
    DRAM Timing Mode [2N]
    ---
    DRAM Bus Voltage [1.60~1.65v] ± use closest value available ; per Rated spec voltage


    1 and 2 didnt work..3 didnt work at bus voltage 1.6 and 1.62..bsod after prime95..i noticed my computer shows 6gb whenever i manually set the bus voltage and 4gb whenever the voltage is on auto. im a little worried about going as high as 1.65v though. the range on them are btn 1.5 and 1.6...i assume going over 1.6v is the danger factor of oc'ing and is worth a shot?

    currenty its running stable at all auto setting minus manually setting bus at 1.6 and qpi at 1.35. the auto timings are currently 8-8-8-20 but cpu-z is telling me its running at a frequency of 534.5mhz..
  15. What EXACT Part-Number Mushkin do you have including how many sticks in total? Are there any other sticks or sets mixed in?

    Please provide a link to them -- this is like guessing otherwise.
  16. Sorry i thought i had already dont that. must have been another post..

    http://www.newegg.com/Product/Product.aspx?Item=N82E16820226034

    that exact set, thats where i bought it from
  17. Mushkin Enhanced 998659
    1600 9-9-9-24 @ 1.6v at Rated Frequency

    If the following fails then you've got a problem with your RAM. Oddly, they are not listed as XMP so don't use that setting -> http://www.mushkin.com/Memory/Blackline/998659.aspx

    Your statements clearly are that of low DRAM Voltage and/or {IMC} QPI Voltage are the problem(s) -> "1 and 2 didnt work..3 didnt work at bus voltage 1.6 and 1.62..bsod after prime95..i noticed my computer shows 6gb whenever i manually set the bus voltage and 4gb whenever the voltage is on auto. im a little worried about going as high as 1.65v though.."

    No, 1.65 vs 1.60 DRAM will NOT damage your RAM; 1.60 RAM can go to 1.90v or +0.30v before any damaging longterm impact. I much rather have a higher DRAM {RAM} than a high QPI {CPU IMC} voltage. The QPI is much more 'damaging' longterm to the CPU and the QPI has a lower tolerance.

    For example, I would by a factor of 20X have DRAM Voltage 1.65v or even up to 1.70v verses 1.62 DRAM with 1.35v QPI which to me is high even for 1.65v RAM using 6-sticks on the X58. A QPI > 1.40v is considered damaging with the CPU at most OC and 9/10 makes the likelihood of a BSOD very high.

    Therefore if STABLE: DRAM Voltage ~1.65v and QPI Voltage ~ 1.25v works then eureka!!!

    [1] Easy - but might Post fail or BSOD {XMP RAM: 3 sticks no problem, 6 sticks can be an issue}:
    Ai Overclock Tuner [X.M.P.]

    [2] Manual Speed with Auto Timings:
    Ai Overclock Tuner [Auto]
    DRAM Frequency -> [DDR3-1600 MHz]
    DRAM Bus Voltage [1.65v] ± use closest value available ; per Rated spec voltage
    QPI/DRAM Voltage {IMC voltage} 1.25v~1.30~1.35v

    [3] Full Manual:
    Ai Overclock Tuner [Manual]
    DRAM Frequency -> [DDR3-1600 MHz]
    DRAM Timing Control /Enter

    DRAM CAS# Latency [9]
    DRAM RAS# to CAS# Delay [9]
    DRAM RAS# PRE Time [9]
    DRAM RAS# ACT Time [24]
    -
    DRAM Timing Mode [2N]
    ---
    DRAM Bus Voltage [1.65v] ± use closest value available ; per Rated spec voltage
    QPI/DRAM Voltage {IMC voltage} 1.25v~1.30~1.35v
  18. 1.64 with qpi at 1.3 made my bios reset...i got a black screen checking for floppy, cd-rom, then usb...i finally put in the usb with my most recent bios and then i reset the computer and my bios had default settings..
  19. Since your RAM is requiring high voltages just to remain semi stable IMO it needs to be RMA to Mushkin. I noticed yesterday that there is a revision 'B' so my assumption is that something wrong with your non-B series.

    The calculation for QPI/DRAM = DRAM Voltage - 0.30v ± 0.05v.

    I would have zero toleration for the instability -- assume that some other BIOS 'tweak' not posted here is in play. In other words, everything is Default and only the above is changed in the BIOS -- except things like AHCI or CPU Fan, etc...
  20. well if qpi has to be within .3v of the bus then technically i should not exceed a bus of 1.65 (it rounds to 1.66 in the bios) that would give me a qpi of 1.36 which in your opinion is kinda pushing it right? ...ill see if mushkin can do anything for me..
  21. See the variance I listed QPI/DRAM = DRAM Voltage - 0.30v ± 0.05v. BIOS rounding goes both ways up and down. You can run your RAM outside of the parameters I's suggested -- it's your rig.

    Bottom-line, if your 1.6v requires your listed voltage then the RAM is not functioning properly. If you had 4X4GB or 6X4GB with the DIMM and RAM fully maxed-out then yes often additional voltage is required.
  22. I tried each stick. not a single one can run at the rated 1600 frequency. however, it is pretty stable at 1333 at rated timings and qpi at 1.35 and bus at 1.66. when i tried to oc the cpu, i set the bclk at or below a value that would put my ram freq at or below 1333 and anything near a ram freq of 1333 wont run stable. This is at 1.66v. its got to be bad ram right? or could my mb be causing this.

    EDIT: i think i wanna turn my back on mushkin. its a loss to buy new ram but i feel it necessary in the long run. whats your opinion on these?

    http://www.newegg.com/Product/Product.aspx?Item=N82E16820231276

    i think my computer would be more stable with 1333 ram considering it will only run 1600 with an oc. i do plan to oc but i heard the difference between 1333 and 1600 is almost impossible to notice.
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