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Underclocking due to CPU?

Discussion in 'Memory' started by Kethridge, 20 Apr 2010.

  1. Kethridge

    Gangster

    Joined: 14 Apr 2010

    Posts: 322

    Hello all this is my first post and I have a bit of a problem!

    I am putting together a new system and think I may have made a mistake.

    I bought the Asus M4A78T-E motherboard which is compatible with DDR3 12800 1600. I rechecked this on crucial's memory compatibility tool and ordered myself a nice set of 4GB kit (2GBx2), Ballistix 240-pin DIMM, DDR3 PC3-12800. Link - http://www.crucial.com/uk/store/partspecs.aspx?IMODULE=BL2KIT25664BN1608

    Now here comes the problem. I've bought an AMD Phenom II x4 945 3.0ghz to go with this system, it arrived today. I've now found out that the AMD Phenom II x4 945 3.0ghz only supports up to 1333 DDR3. I know the system will underclock and everything will run ok BUT my question is -

    Will it have an adverse affect on the system's performance compared to running 10600 1333?

    And why? (I don't understand memory timings too much)

    Cheers in advance,

    Keth.
     
  2. Kethridge

    Gangster

    Joined: 14 Apr 2010

    Posts: 322

    Bumpo!

    No-one able to shed any light on this?
     
  3. blaineoliver

    Hitman

    Joined: 29 Jul 2009

    Posts: 704

    Location: Near London

    Run it at 1333, but with tighter timings than the 1600 timings its rated, will run best for amd, they run best with 1333 and tight timings rather than 1600.
     
  4. Kethridge

    Gangster

    Joined: 14 Apr 2010

    Posts: 322

    As I said I don't really understand memory timings too much but have read the overclockers memory FAQ.

    How do I change the timings?

    What do you mean by 'tighter'?

    Would changing the timings cause any problms (ie overheating)?
     
  5. DavieJG

    Hitman

    Joined: 24 Sep 2009

    Posts: 619

    timings are changed in the BIOS (del, f2 or something during start-up, see motherboard manual or look for on-screen prompt)

    the timings are listed a a number which represents the number of clock cycles required to perform an action.

    tighter timings means a small number of cycles for an operation i.e. faster.

    if the timings are set too fast, the system can become unstable or fail to boot, but wont do anything that will do any permanent damage. restoring the timings to default will allow the system to run again.

    playing with memory speed has very little real world performance gains as most apps simply cant stress the default settings enough.
     
  6. Kethridge

    Gangster

    Joined: 14 Apr 2010

    Posts: 322

    So just to double check, there is absolutly no way I can do any permanent harm to my memory (or anything else) by messing with the timings?
     
  7. Devrij

    Capodecina

    Joined: 23 Jul 2009

    Posts: 13,742

    Location: Bath

    Nope, the worst that can happen is your pc won't boot or will crash every now and then, meaning you'd have to revert to stock settings. If you test it when you adjust your timings, you can make sure it's stable and won't have these problems. Run CPU-Z (get it here)and go to the memory SPD tab, it should have a list of speeds and corresponding timings like this (eg, 5-5-5-15 for my memory speed of 1066, keep in mind ddr is shown as half the speed because it's dual data rate)
    [​IMG].
    That should tell you what timings to set for that lower speed.

    Once you've done that, download prime95 and run the blend setting for an hour or two to test stability. No errors means you're all good. Keep an eye on cpu temperatures while running prime btw, but at stock speeds you should be just fine.
     
  8. thingemajib

    Wise Guy

    Joined: 18 Feb 2009

    Posts: 2,463

    Location: Behind you

    i thought tests showed newer AMDs werent affected as much by timings?

    if you want 1600mhz, try overclocking (theres about a million threads on here...).

    generally, if you run the sticks slower (ie 1333mhz), you should get tighter timings. ie thise sticks claim 8-8-8-24 @1600, so they should be capable of 7-7-7-something at 1333. the tighter timings should balance out the slower speed anyways, even thought both of these have next to no effect on performance.
     
  9. Kethridge

    Gangster

    Joined: 14 Apr 2010

    Posts: 322

    Thanks for the help guys! Very informative answers.

    When you say they have next to no effect on performance, what are we talking? 5%?
     
  10. Devrij

    Capodecina

    Joined: 23 Jul 2009

    Posts: 13,742

    Location: Bath

    minimal bro, but it would niggle at you knowing you could have a tiny bit more wouldn't it? Maybe that's just me :p
     
  11. Kethridge

    Gangster

    Joined: 14 Apr 2010

    Posts: 322

    No it's not just you!!

    How do I unlock the full 1600Mhz that the RAM and motherboard are capable of?

    (Am a real beginner at overclocking so the more detailed the information the better! And yes I have been reading many different articles but have only succeeded in making my head hurt!)