Phenom 550 : Need Help Stabilizing the 4th core

I've just bought an AMD Phenom II X2 550, and successfully unlocked another core, so I have cores 0,1,3 working just fine without editing anything.

When I activate the 4th core though, when I have 0,1,2,3 all working, the windows loads, but just minutes after I log in my account it restarts without warning, also before it restarts the whole system is slow, some programs refuse to open "Kaspersky + Firefox", and the login music has some noise in it.

I've read somewhere that there's a chance to stabilize the 4 cores if I increased the Vcore voltage, and also by increasing the north bridge voltage I think, and finally by playing around with the cores calibration.

So I increased the Vcore voltage from 1.35 to 1.38, didn't work. I didn't try to increase the north bridge voltage because I'm not sure I understood that stabilizing topic well. And finally I went on the calibration from -2% to -4% etc, till -8%.

At -4% the music noise was less, barely none, the system wasn't much better though, just a little.

Anyway I don't know anything about overclocking so I'm really afraid of doing anything dangerous, so if there's something I can do to stabilize the system that would be great help, I just wanna be sure before increasing some voltage or fry my pc xD

Motherboard : Asus M4A78LT-M LE
Ram : Kingston 2 GB DDR3 1333
CPU : AMD Phenom II X2 550
Normal CPU temperature : 40 C
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  1. I would say try raising the voltage a bit more try 1.4 on the VCore and mess with the ACC settings. You should not have to touch the northbridge voltage unless you are overclocking too then you might need to add a little to get your OC stable. You can go all the way up to 1.5 on the Vcore with out causing damage to the CPU but remember that more volts equals more heat so keep an eye on temps dont let them get over 70C. If raising the voltage doesn't get it stable then the 4th core might be defective and there is nothing you can do to get it stable.
  2. Yup I've noticed that the more voltage the more heat there is, um I got 2 questions now :

    Should I mess with the ACC settings while the Vcore is over the normal ? or do this and that in a separate time ?

    Also the ACC calibration is from -12% to +12%, I don't what does that percent mean but anyway from what to what should I try it ? -2% to -8% ?
  3. Its all trial and error as to which setting will work and like I said before you can safely raise the voltage up to 1.5, but if its not stable with 1.4 I doubt that more voltage will help.

    I would really recommend getting a bigger cooler for that processor. You dont have to get the biggest and most expensive, but you should definitely get a bigger cooler for it.
  4. I'll buy a better cooler + power supply within 2 weeks to make the CPU better, thanks for the help and the advice :)
  5. I just really don't understand. I'll spend money buying better coolers and a better power supply so I can try to get my X2 to do things and X4 should do. Wouldn't the logical thing to do at this point would be just buy an X4?
  6. I'm not buying them to make turn it into X4, it's hot in Egypt and whatever CPU I have I need a better cooler. Also I have a cheap PSU so it's safer to get better one. So even if I bought a X4 I'll still buy those.
  7. Give us an update on how it works for you.
    We're all curious to know if a better CPU cooler and PSU helps stabilize the 4th core.
  8. I think the 4th core is just defected as I tried to increase the Vcore and did some changes in the ACC but it keeps restarting as soon as it gets to the windows accounts screen, still a good X3 CPU for that price though. When I buy them I'll retry, if there's anything better I'll update here :)
  9. I had similar issues and after trying EVERYTHING ,
    with my big surprise ,
    the key was in fact TO LOWER THE V/CORE instead of raising it!!!!
    my default 1.30v were somehow to aggressive and if i unlocked the 4 cores
    i would experience applications crash or even blue screens of death
    but as soon as i lowered it to 1.225v magically everything was more stable.
    also check this guys talking about the cpu/nb frequency and voltage he
    did a great job here

    let us know
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