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AMD Phenom II x2 555 unlocked with weird results (please help)

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August 19, 2011 9:14:24 PM

I have tried to unlock my Phenom II x2 555 to a Phenom II x4 B55 but I am getting strange results.

Windows starts fine with all 4 cores unlocked and working at 3.2Ghz with v1.35 but stalls during Prime95 testing. The weird thing is, it seems like all 4 cores are are working alright though.

I have turned the 4th core off and I am able to run Prime95 with 3 cores at 3.2Ghz with v1.35 no problem.

I have turned the 3rd core off and I am able to run Prime95 with 3 core at 3.2Ghz with v1.35 no problem.

So it seems like the two unlocked cores work fine but only when I run them one at a time.

I have also tried running Prime95 with all 4 cores at v1.4, v1.45, and v1.5 but it still stalls.

So my question is how come I can't seem to get all 4 cores working together even though it seems like there is nothing actually wrong with any individual core?

Appreciate any feedback. Thanks.



a b à CPUs
August 19, 2011 9:22:08 PM

It stalls? But no BSOD? Also, you don't want to up the voltage arbitrarily like that, you could run into some serious problems, better to take it 10-20mV at a time. Did you adjust the CPU-NB voltage? Trying inching that up in parallel with the core voltage, maybe to about ~1.37, and then try that. If that doesn't work, then give it a bit more, perhaps about ~1.39.
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August 19, 2011 9:28:58 PM

Yes, it stalls. I can't input any keyboard or mouse commands and screen seems to freeze. Maybe I haven't let it run long enough to get the BSOD, I restart soon after it stalls.

My CPU/NB voltage is v1.2 right now and don't really want to mess with it. Can you explain why the CPU/NB voltage would be a factor in whether the CPU is able to run all 4 cores?

Thanks for the quick response. :) 
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August 19, 2011 10:17:03 PM

To be quite honest, I can't explain exactly why, I just know that it has to be done for a stable overclock, if that OC requires raising the CPU voltage, that is. What motherboard are you using? I'd try looking up OC guides for your specific model and do something along those lines as far as voltages for stability.
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August 19, 2011 10:18:06 PM

cuecuemore said:
It stalls? But no BSOD? Also, you don't want to up the voltage arbitrarily like that, you could run into some serious problems, better to take it 10-20mV at a time. Did you adjust the CPU-NB voltage? Trying inching that up in parallel with the core voltage, maybe to about ~1.37, and then try that. If that doesn't work, then give it a bit more, perhaps about ~1.39.


I tried again with all 4 cores at 3.2Ghz with CPU v1.35 and CPU/NB v1.3 from v1.2 but it still stalled Prime95.

If I am going to keep trying, how can I tell what to move up next? The CPU voltage or CPU/NB and what is the safe range for CPU/NB voltage? My motherboard says the Min and Max is dependent on CPU so that's not helping me.


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August 19, 2011 10:23:06 PM

cuecuemore said:
To be quite honest, I can't explain exactly why, I just know that it has to be done for a stable overclock, if that OC requires raising the CPU voltage, that is. What motherboard are you using? I'd try looking up OC guides for your specific model and do something along those lines as far as voltages for stability.



So you're saying that the CPU/NB voltage should be raised only if I raise the CPU voltage also?

I got a new 900 series AMD motherboard so I don't think many people have one yet, its the ASUS M5A97.
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a c 111 à CPUs
August 19, 2011 10:28:07 PM

Every chip is a little different, but going beyond 1.3v on the NB volts is really uncomfortable for me.

My PhII X2 unlocked and under-volted like a champ - it's not always the case with every chip. An X3 is still a stout chip, especially if you can crank up the speed and NB/IMC.

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a b à CPUs
August 19, 2011 10:31:33 PM

I'm not sure if the new boards are different, but on mine, the MSI NF980-g65 AM3, I have to set the CPU-NB voltage at the same level as the Vcore to get a stable overclock. But I'd look around if I were you to see what the voltage for the CPU-NB should be set at for the new boards.
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August 19, 2011 10:33:02 PM

I have the same unlocked CPU, never bothered to run Prime95. It's solid as a rock in everything I do, couldn't care less about Prime 95. If you don't OC, set the CPU voltage to 1.25V (for decreasing the temps) and forget about it.
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August 19, 2011 10:39:33 PM

Is unlocking synonymous to overclocking? I'm not interested in overclocking (yet).

I'm interested if anyone has heard of actually having to modify any other setting in the BIOS to get a CPU unlocked successfully other than CPU voltage?
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August 19, 2011 10:44:22 PM

You do realize that many, if not most, of the dual and tri core processors based on the deneb core parts have disabled cores for a reason.

The likely explanation it the cores were disabled due to a defect which you are now encountering.
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a b à CPUs
August 19, 2011 10:45:58 PM

No, they're not synonymous, but they are related concepts. There is a reason that you CPU shipped as an X2 instead of an X3 or X4, that being that at the fab, they decided they didn't want to guarantee it for 3 or 4 cores. So they locked two of them down and said "buyer beware." (EDIT: I mean as far as the stability of unlocked cores, 2 should run fine) There are plenty of folks here who know way more about this than I do (I run an X4 965) so I may be way off base in suggesting that you overvolt.
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August 19, 2011 10:55:06 PM

FALC0N said:
You do realize that many, if not most, of the dual and tri core processors based on the deneb core parts have disabled cores for a reason.

The likely explanation it the cores were disabled due to a defect which you are now encountering.



I do realize that but like I said in the original post, I tested each individual core separately so it seems like the cores are not the problem but something to do with running 4 cores at once.

I've searched and haven't come across a problem like mine, usually one or both dormant core is defective in some way and deactivating that core solves the problem.

Has anyone had to increase their CPU voltage to actually get unlocked cores stable? Everywhere I look it seems like people only have to mess with CPU or CPU/NB voltage if they want to overclock.
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August 20, 2011 4:03:03 AM

Why not just buy a quad they are cheap. There is a reason 2 cores are disabled.
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August 20, 2011 4:53:42 AM

Lonecontrol said:
I do realize that but like I said in the original post, I tested each individual core separately so it seems like the cores are not the problem but something to do with running 4 cores at once.

I've searched and haven't come across a problem like mine, usually one or both dormant core is defective in some way and deactivating that core solves the problem.

Has anyone had to increase their CPU voltage to actually get unlocked cores stable? Everywhere I look it seems like people only have to mess with CPU or CPU/NB voltage if they want to overclock.


Why would you increase the voltage? You said the cores were working.

Defects are not just in the cores, but the uncores as well. It looks to me like there is a defect in the uncore somewhere that makes the 4 cores not run happy together.

If you really want to test that voltage thing, don't increase the voltage. Decrease the speed of the processor. Its 3.2 stock, so decrease it to 2.0 ghz. That will tell you if its a voltage problem without risking damage. But I highly doubt its the problem.
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August 20, 2011 5:35:03 AM

FALC0N said:
Why would you increase the voltage? You said the cores were working.

Defects are not just in the cores, but the uncores as well. It looks to me like there is a defect in the uncore somewhere that makes the 4 cores not run happy together.

If you really want to test that voltage thing, don't increase the voltage. Decrease the speed of the processor. Its 3.2 stock, so decrease it to 2.0 ghz. That will tell you if its a voltage problem without risking damage. But I highly doubt its the problem.


That was a great idea. I unlocked all 4 cores and set them to run at 2.3Ghz with v1.3.

Prime95 this time ran like a microsecond longer that usual but still froze up the computer.

I guess there is something wrong with the circuitry needed to run all 4 cores at the same time. So I have to settle with a X3 instead of a X4 but I paid for a X2 so I'm happy. :sol: 

Thanks for the help.
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August 20, 2011 5:35:45 AM

Best answer selected by Lonecontrol.
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August 20, 2011 8:17:06 AM

This topic has been closed by Mousemonkey
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