Understanding tRAS

By lpmjames
Feb 3, 2010
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  1. ok so i have been doing research on how to clock my system but now i need some forum help.. my current frequency is set to 133mhz and i want to set it to 166 so i can process faster of course. but i am afraid of not being able to boot up again.. (happened before.. lame i know) what do i need to do to ensure my motherboard being stable enough for such a change.. .. HELP!!
    ohh yea... understanding tRAS... so my question is my memory shows the clock speeds in cpu id @ 2.5 (cl) 3(trcd) 3 (trp) 6 (tras) .. @ 133. but it then shows that my mem is capable of 166mh @ 2.5, 3, 3, 7 wut does this mean and is this properly set... seems wierd.. but thats y im asking for help..
  2. dividebyzero

    dividebyzero trainee n00b Posts: 4,816   +651

    Regarding the RAM : CPUID is showing you the presets that the RAM has programmed into it.
    the two programs are DDR-266 @ 2.5-3-3-6 and the slightly faster bandwidth (with very slightly looser timings) of DDR-333 @ 2.5-3-3-7

    To change from 133 (DDR-266) to 166 (DDR-333):

    Under the "Advanced" tab in your BIOS
    Change "CPU/Memory frequency ratio" from "Auto" to the appropriate divider for DDR-333
    Scroll down to:
    "SDRAM Configuration" - change from "by SPD" to "User defined"
    "SDRAM Active Precharge Delay" - change from "6T" to "7T"

    Press F10 to save and exit.

    Any problems then post back preferably with your RAM's manufacturer and model

    This should be enough to enable the DDR-333 to run
    Here's an article that explains some aspects of RAM timings
  3. lpmjames

    lpmjames Newcomer, in training Topic Starter Posts: 155

    thanks for that stepbystep... question is whats the result... should i yeild a higher processing speed or just my memory will be faster???
  4. dividebyzero

    dividebyzero trainee n00b Posts: 4,816   +651

    You may see a very very slight increase in performance - not significant in any meaningful way. However it's free performance regardless of how small the increase.
  5. lpmjames

    lpmjames Newcomer, in training Topic Starter Posts: 155

    im using 2 kingston 256mb pc2700 and 1 nanya tech 256mb pc2700 cards .. btw...
  6. lpmjames

    lpmjames Newcomer, in training Topic Starter Posts: 155

    and in my bios i get the option to directly choose my processing speed.. from 1000 / 1400 (currently set) / or 1750... by changing this im thinkin it works kinda hand and hand with changing the above setting .. am i correct in thinking this and if so will it be ok when and if i make this change...?
  7. dividebyzero

    dividebyzero trainee n00b Posts: 4,816   +651

    THe dividers may be automatically set as you have only six combinations to work with ( 3 CPU and 2 RAM). I would try the 1400/DDR-333 first - if all good then you could go for the 1750/DDR-333. I'm assuming that your mixed RAM set is fully stable at the moment, so I'd make sure the changed RAM timings are working with both RAM modules types as mixing RAM types can be problematic -not so much with DDR- but I'd still take it a step at a time for the sake of troubleshooting if the change doesn't work. Changing CPU speed and RAM timings together and encountering a problem means troubleshooting two possible avenues.
  8. lpmjames

    lpmjames Newcomer, in training Topic Starter Posts: 155

    ok ... so strange thing is my bios wont allow me to set it from 6t to 7t... only 6t to 5t ... and yes its very stable.. i dont think this motherboard is stable enough to run at 333 if it isnt its going to lock up and how will i be able to reverse it
  9. dividebyzero

    dividebyzero trainee n00b Posts: 4,816   +651

    You can try leaving using the RAM at DDR-333 with 2.5-3-3-6.
    The worst case scenario is that the system will not post. You would then most likely nrrd to clear CMOS (see Page 28 in the manual for the procedure) this will reset the BIOS to default levels. If you have made changes to the BIOS then before you start note the settings so you can change them once the system reboots after clearing CMOS.
    The more probable scenario (if the RAM is not stable that is) is that the system will boot ok but the RAM may not be completely stable. Even if it is stable I would strongly recommend that you test the stability using Memtest86

    Memtest

    -Download Memtest86+ here http://www.memtest.org/ then burn the .iso (after uncompressing) to CD with ImgBurn or burning software (needs to be bootable) OR download the executable for USB if your BIOS allows you to boot the system from USB
    -Place the CD in drive (or attach USB drive)
    -Reboot computer, change boot order to CD (or USB), save change, reboot.
    -Memtest will load and test the module. Each pass takes around 10-15min to complete for 1Gb, run 7-10 passes minimum. Tests 2 and 5 within the pass are most likely to find errors and you can order loops of these tests in the options.
    -Stop the test when you're happy that the RAM is stable, reboot back to BIOS
    -Remove CD/USB, reset boot order, save changes, reboot.

    Here's a short introduction and instruction with screenshot

    You may decide that it's not worth the gain, or decide that it's a good introduction into getting a closer understanding of the system.
    I would advise as a matter of course that anyone adding RAM, and/or altering timings, follow a thorough testing and stability regime.
    Memtest is not 100% effective in catching bad timings or RAM as it doesn't take into account the whole system running under load where small voltage changes in northbridge (MCH) and RAM can influence stability, but it will ensure that the RAM is theoretically capable of running at it's new timings and the RAM is error free.
  10. lpmjames

    lpmjames Newcomer, in training Topic Starter Posts: 155

    ok... so now i dont believe its worth the struggle to clock this board or cpu any further... i tried changing the cpu speed setting to 1750 but it wouldnt reboot after that... kinda wierd that this board is an asus a7v333... where can i go to find better info on this boards capability..
  11. dividebyzero

    dividebyzero trainee n00b Posts: 4,816   +651

     
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