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Phenom II 940, M3A78-T FSB overclock problem

Discussion in 'Overclocking & Cooling' started by Guyonskis, Jun 14, 2009.

  1. Guyonskis

    Guyonskis

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    I managed to get my Phenom II 940 to 3.6 Ghz stable just by changing the multiplier to 18x and raising the VCore to 1.5v. I then tried to raise my FSB to 206Mhz (for 3.7) and it failed prime95 blend test. Anything more and it would BSOD or just crash. I've tried raising memory/NB voltage to 1.2v/1.4v which didn't help. I tried lowering the multiplier to 17x and raising the FSB to 220, same thing. I also tried raising/lowering my NB multiplier, no difference. I limit the memory frequency and let the board choose my timings: FSB:DRAM 1:2 (seems low?), 5-5-5-15-23 currently. My temps are good CPU idle 28C, load 34C.
    Any ideas on what is causing these problems when I raise the FSB?
    Are BSOD/crash/prime95 failure caused by different things?

    I'm a semi-noob at overclocking so maybe I'm missing something... what do I need to consider when raising the FSB?

    Thanks in advance!
     
  2. demonkevy666 New Member

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    it' not FSB it's HTT or hyper transport reference speed.
    can you read the bsod before it go's ?

    I don't know what speed your ram is, but some times pushing it some ram hates it.

    I get about 3.740ghz @ 1.475v but I'm running vista ultimate 64 bit.
     
  3. cdawall where the hell are my stars

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    its HTT no HHT ;)


    sme 940's were dogs a oc'ing put the volts around 1.55v and NB volts around 1.4v
     
  4. demonkevy666 New Member

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    why aren't we using the R & S ??? lol

    it should be HTRS.
     
  5. chuck216

    chuck216

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    Dumb question but if you want 3.7 Ghz why not just use a 18.5 multiplier and avoid all the mismatched HTT bus and ram speed problems? A little extra voltage on the v-core maybe up to 1.525 should get it stable on air.

    You shouldn't need to raise the FSB with a Black Edition chip except to tweak the last little bit of overclock.

    (and yes I know it's "HTT reference speed" now but I'm old school and I'll always call it FSB)
     
  6. Guyonskis

    Guyonskis

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    @ demonkevy666 - I think the BSOD was something to do with memory

    My old CPU stopped working so I'm hesitant to raise the voltage to much. The spec for the 940 gives a range up to 1.5v so I would prefer to leave it at that. Is the only danger of voltage from heat or could it damage a processor in other ways?
    Would the v-core requirement be the same for 18.5 x 200 as 18 x 206 or 17 x 218?
     
  7. Exeodus

    Exeodus

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    It has been my experience that ASUS boards don't overclock the bus very far past 200 on Phenom II class processors. Most 940's seem to acheive max stability around 3.6ghz. They will game and bench higher, but won't pass most stress tests.
     
  8. crunchie

    crunchie New Member

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    Max safe vcore on the 940BE is actually 1.425 according to AMD.
    Read it on the pdf here; http://www.amd.com/us-en/assets/con...d_tech_docs/GH_43375_10h_DT_PTDS_PUB_3.18.pdf
    I always thought it was 1.55, but there you go.
    Surprised you cannot go higher on your clock though. I can get 4.0GHz on 1.475vcore.
    Set your vcore to something like 1.45-1.5 and then keep raising your multi until you have problems with stability. It's up to you then if you want to up the vcore, or accept that your chip does not want to go any higher.
    3.6 cpu and 2.6 cpu/nb is a nice OC to settle on imo.
     
  9. cdawall where the hell are my stars

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    mine will do 300HTT tested by me on a 955BE
     
  10. Guyonskis

    Guyonskis

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    That's sad to hear! You're right, 3.7 was stable enough to game and run 3Dmark... just failed the stress test.

    They're big liars lol http://products.amd.com/en-us/Deskt...&f5=&f6=C2&f7=45nm SOI&f8=&f9=&f10=False&f11=

    I guess I shouldn't complain about 3.6 ... I'm just curious about how far my air cooling can get me. Haf 932 is awesome!
     
  11. Guyonskis

    Guyonskis

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    With what voltages? Did you change other multipliers, like NB?

    I think I may need to get me a M4...
     
  12. cdawall where the hell are my stars

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    multi was dropped and the NB was@10x HTT link@7x


    HTT volts@1.33v, NB@1.45v, cpu@stock
     
  13. Fatal

    Fatal

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    Maybe post some screen shots of CPUz from looking at your rig you have 4x1GB sticks. That would be a problem depending on if they are overclock you have to drop the bandwidth to the next lowest clock. So if they are 1066>800 or 800>667 or 667>533 what are the sticks rated to run? This will allow others to help you better :D

    [​IMG]
     
    Last edited: Jun 15, 2009
  14. Guyonskis

    Guyonskis

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    PC6400 800Mhz... can it not go any higher? I believe I tried lowering it to no avail... but I think I changed something else as well that time. I can try only turning my memory down. Won't that affect my overall performance though?

    I'll try to post pics later today.
     
  15. crunchie

    crunchie New Member

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    Try 2 sticks only as well as the cpu is stressed more when all 4 dimms are populated.
    If you find you are more stable at higher frequencies, go for some 2x2 sticks.
     
  16. Guyonskis

    Guyonskis

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  17. Fatal

    Fatal

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    I can get my CPU to beach at 3.7 and 3.8 but far as 24/7 use 3.6 is as high as my CPU will allow. The memory you have did it come all together or is it two kits? That can be a problem if they are two kits. Using one of the sets will help see if the memory is in fact the issue.
     
  18. Guyonskis

    Guyonskis

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    Two kits. :(
    Well if it works well with two sticks I'll have an excuse to buy some fancy RAM!

    Does the order I put them in matter with two kits? I think I put two in the first two slots, and two in the next two. Could this be causing problems?
     
    Last edited: Jun 16, 2009
  19. crunchie

    crunchie New Member

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    If the dimms are colour coded, put one kit in one colour and the other in what's left :)
    Running 4 sticks will stress the cpu more and bring down your OC.
     
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  20. Fatal

    Fatal

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    “Mixing ram is not going to be recommended, it also reduces overall memory performance.”

    http://www.ocztechnologyforum.com/forum/showthread.php?t=46755&highlight=OCZ platinum PC6400 800Mhz


    http://www.ocztechnologyforum.com/forum/showthread.php?t=42686&highlight=OCZ platinum PC6400 800Mhz

    With you running two kits I would say your main goal should be to see if the kits can work as one stock settings first. So install all four and use the stock settings see if your system can run with all four sticks stock setting. Maybe run Memtest or OCCT with the sticks in as well to be sure that it is stable with the four sticks. If so then see how much you can overclock them. I did some looking for those sticks above links. My brother has been running a mixed pair of 1gig Corsairs for over a year and they are overclocked so it is possible. If not then your best bet would be to get a set of 2x2 gig sticks

    Memtest
    http://www.memtest.org/

    OCCT
    http://www.ocbase.com/perestroika_en/index.php?Download

    DDR2 800 (PC2 6400)

    http://www.newegg.com/Product/Produ...0147 1052416064 1052315794&name=4GB (2 x 2GB)

    DDR2 1066 (PC2 8500)

    http://www.newegg.com/Product/Produ...4&bop=And&ActiveSearchResult=True&Order=PRICE

    The price is pretty close depending on what company you go with between 1066 and 800 memory. It can be difficult to run four but has been done good luck.
     
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  21. Guyonskis

    Guyonskis

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    Thanks for all the help! Great links.

    Ok so I tried 206 with only one kit, no improvement.
    I think perhaps something strange is going on with my voltage. I set vcore to 1.55 and pushed the multiplier to 18.5 and it seems stable so far (35c load). CPUz shows 1.55v but pc-probe is only showing 1.51v. Maybe I'm not getting the voltage I ask for and that's limiting my OC. I'll test it later with 18x, 206 FSB.
    If the temps are good does it matter how high the voltage is? Can CPU damage occur at lower temps?

    I think I may buy 2x2 corsair dominators pc8500 anyways... the fans will look awesome and I won't have to worry about memory anymore.

    Edit: 18.5 is not stable, failed in less than 3 hours. Sigh.
     
    Last edited: Jun 17, 2009
  22. Fatal

    Fatal

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    As I stated I cant get anything higher than 3.6 in OCCT stress test. Sure I can run it at 3.7-3.8 and will be fine will not crash one bit. 1.55v seems a bit high I can get 3.7 with 1.48v and 3.8 with 1.48v-1.50v. The only issue is its not OCCT stable. Which program are you using to check to see if its stable? If you are getting 35c load your rig has some serious cooling :rockout:. Which slots are you using the ram in? I think I read in those links I sent you that the black ones were better to use.

    I will have to research your board more so I can be more help for you. Maybe some one in the forums here has your board and will step in to assist as well.

    Edit:
    Is Cool n quiet and TLB Fix disabled just making sure cause they have to be.
     
    Last edited: Jun 17, 2009
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  23. Guyonskis

    Guyonskis

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    So when I read about people claiming 3.8, it just means that they can boot windows? THAT has never been an issue... I haven't tested how far I can go till I can't boot. I use Prime95 blend test. How can I test if my settings are usable for normal use? 3Dmark06?

    I can't believe I only have 35c with air, under load, I'm starting to doubt pc probe is giving me accurate readings. I'll install a bunch of other monitoring programs when I get home. If it's true though then I love my new Haf 932!

    I think I'm using the yellow ones (recommend settings)! I have to read the forum more closely. I rather use black, especially if I get the dominators since my cpu heat sink partially goes over the yellow and I don't think they will fit.

    I saw some forums with my board and I couldn't get it to pass prime95 with their settings... I don't remember if they stress tested or not.

    Funny, I just remembered about cool and quiet today. One of the settings I had wouldn't even post so I had to reset my bios. I forgot to check those settings! If they are enabled by default, then they are enabled now.
     
  24. Guyonskis

    Guyonskis

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    Where did you see this? I can't find it.
     
  25. cdawall where the hell are my stars

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    [​IMG]


    no bus clock issues on my M4A78T-E
     

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