AMD Phenom II X3 720 Unlock

Good day all,

I recently purchased a new system for gaming et cetera, and decided to go with the AMD P2 X3 BE. After a bit of use, I figured I'd attempt to unlock the fourth core and see what happens. Luckily I didn't have my hopes up too high, because it crashed at the login screen. I then attempted to isolate the 'bad core', but without any luck. Here's what I tried:

ACC: Auto, Per Core
Unleashing: Enabled (when on Per Core: [ [0,1,2], [0,1,3], All Cores ] were attempted)

With either core2 or core3 enabled, or if all 4 cores are enabled, the system crashes regardless at the login screen. I get a BSOD message:

"A clock interrupt was not received on a secondary processor within the allocated time interval."

I haven't tried messing around with any voltages, and am only slightly overclocked. So I'm wondering, does this mean that either core0 or core1 is dysfunctional, or am I doing something wrong?

PC Specs
MB: ASUS M4A79XTD EVO
CPU: AMD Phenom II X3 720 BE
MEM: 4GB OCZ DDR3 PC3-10666 / 1333 MHz
VID: ASUS ATI Radeon 4890 1GB GDDR5
HDD: Seagate Barracuda 7200.11 SATA 1TB
PSU: OCZ GameXtreme 650W
31 answers Last reply
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  1. Ok first of all, remove any overclock you have.

    Then enable the 4th core and see how it goes. If it boots, gz you've got a 4th core for free.

    If it crashes, you might need more voltage even at 'stock'. Try a little bit more, 0.05v or so and see if it boots up.

    It is entirely possible you really got a bad 4th core or something, but give it a go anyway.
  2. Thanks for the quick reply ohreally,

    Here's what I've just attempted:

    1. Set CPU multiplier to 14.0x (stock 2.8GHz)
    2. Incremented VCore from 1.325v to 1.4v; no luck here.
    3. While keeping VCore at 1.4, incremented VCPU/NB from 1.2v to 1.35v; still no luck.
    4. Underclocked incrementally down to 12.0x (2.4GHz); still no luck.

    And I still don't understand why manually enabling cores 0,1, and 2 (or 0, 1, and 3) still BSOD with the same error message as enabling all 4 cores, unless core 0 or 1 are defective.
  3. It seems your chip will not unlock the 4th. Please understand that not all 720s will unlock.

    I only had to change the ACC setting for mine to unlock.
  4. Hi newcomer and welcome to the Tom's hardware forum.

    Maybe this can help you.
  5. Sounds like you got one of the chips with an actual bad core - on mine all it took was enabling the Hybrid mode ACC and turning it on in the Bios of my Gigabyte MOBO and it has been running stable at 3.0ghz. for about a month now - ( benchmarks - http://i212.photobucket.com/albums/cc189/JDFanning_bucket/benches01-1.jpg ) - I'm still using the stock heatsink so haven't pushed the overclock anymore but I must say this setup with a sapphire 5770 is a great improvement over my old 3200+ athlon with an AGP 7800GS videocard.
  6. What is 'unleashing' ???

    What BIOS are you using?

    A cruise by XS may determine if the newer Asus BIOS versions for that mobo 'lock out' unlocking ...
  7. Steve_L said:
    Thanks for the quick reply ohreally,

    Here's what I've just attempted:

    1. Set CPU multiplier to 14.0x (stock 2.8GHz)
    2. Incremented VCore from 1.325v to 1.4v; no luck here.
    3. While keeping VCore at 1.4, incremented VCPU/NB from 1.2v to 1.35v; still no luck.
    4. Underclocked incrementally down to 12.0x (2.4GHz); still no luck.

    And I still don't understand why manually enabling cores 0,1, and 2 (or 0, 1, and 3) still BSOD with the same error message as enabling all 4 cores, unless core 0 or 1 are defective.


    Was the cpu fine at stock out of the box, ie 3 cores at 2.8ghz?
  8. xsever said:
    It seems your chip will not unlock the 4th. Please understand that not all 720s will unlock.

    I only had to change the ACC setting for mine to unlock.

    I wasn't expecting it to unlock; that would have been a nice bonus, though.

    Anonymous said:
    What is 'unleashing' ???

    What BIOS are you using?

    A cruise by XS may determine if the newer Asus BIOS versions for that mobo 'lock out' unlocking ...

    Unleashing is ASUS terminology. As for BIOS, it's v0605, 09/21/2009, which is confirmed to work just fine.

    Quote:
    Was the cpu fine at stock out of the box, ie 3 cores at 2.8ghz?

    Yes, the CPU runs fine at stock settings, and runs relatively cool when overclocked, as well.
  9. Quote:
    Yes, the CPU runs fine at stock settings, and runs relatively cool when overclocked, as well.


    Bad luck to you, you have an X3 that isn't stable with the 4 core unlocked.
  10. Don't give it up yet.

    Unlock the 4th core, shove the voltage up to 1.5v. Phenom II's are comfortable at 1.5v and beyond. If you still can't boot at that, then you can pretty much confirm your 4th core is gone beyond repair.
  11. ^The safe voltage for AMD processor is 1.5V, you can set more, but isn't safe.
  12. Yep it's fine though really.

    What's the worst that can happen? The cpu blows up and he has to send it back for a replacement that might unlock the 4th core? :D
  13. ^jajaja, the blows up is for OC and the warranty don't apply for this.
  14. Nobody is going to tell them though, right? :D
  15. No, but AMD isn't an idiot for not know that the processor was dead for OC.
  16. Quote:
    Don't give it up yet.

    Unlock the 4th core, shove the voltage up to 1.5v. Phenom II's are comfortable at 1.5v and beyond. If you still can't boot at that, then you can pretty much confirm your 4th core is gone beyond repair.


    I will crank to VCore up to 1.50 and re-post after my PC crashes, then. ^^
  17. Steve_L said:
    I wasn't expecting it to unlock; that would have been a nice bonus, though.


    Unleashing is ASUS terminology. As for BIOS, it's v0605, 09/21/2009, which is confirmed to work just fine.


    Yes, the CPU runs fine at stock settings, and runs relatively cool when overclocked, as well.



    Did you try lower Vcore ? My unlocked 4 core @ 1.150 v .
  18. I got the X3 425 and was able to unlock the 4th core and the L3 cache, but I was lucky. Not bad for a $76.00 chip. It seemed to work ok but when I went to turn the computer on one day I had to hit the power button a couple times to get it to boot. Not sure what that was all about so I set it back to stock. It is a gamble and some unlock and some don't. And even if they unlock they are not always stable. The X3 720BE is a very capable cpu so I would not even bother with trying to unlock the 4th core. Just over clock it.
  19. I tried everything from 1.325 to 1.500 V, and I don't want to go over the 1.5V mark as I doubt it will do any good.

    Quote:
    Did you try lower Vcore ? My unlocked 4 core @ 1.150 v .

    Now that you mention it, the only time I was able to actually get onto my desktop and view task manager with the 4 cores was at the lower CPU voltages, although it may have been just luck (PC crashed at login screen after I increased voltage a bit). I started at 1.325V, which I believe is the standard X3 voltage.

    I will attempt 1.150V and increase incrementally. At this point I'm just killing time before bed. ^^

    UPDATE: Windows instantly crashes at loading screen when set at 1.2V or below. Increasing incrementally from there gave the same results as before (BSOD at login screen, clock interrupt timed out).

    I think I've wasted enough time ensuring that my 4th core is actually dead. So, anyone want to recommend a good CPU HS/Fan? I'm using the stock one right now, and it's rather inefficient and noisy.
  20. Steve_L said:
    I tried everything from 1.325 to 1.500 V, and I don't want to go over the 1.5V mark as I doubt it will do any good.


    Now that you mention it, the only time I was able to actually get onto my desktop and view task manager with the 4 cores was at the lower CPU voltages, although it may have been just luck (PC crashed at login screen after I increased voltage a bit). I started at 1.325V, which I believe is the standard X3 voltage.

    I will attempt 1.150V and increase incrementally. At this point I'm just killing time before bed. ^^

    UPDATE: Windows instantly crashes at loading screen when set at 1.2V or below. Increasing incrementally from there gave the same results as before (BSOD at login screen, clock interrupt timed out).

    I think I've wasted enough time ensuring that my 4th core is actually dead. So, anyone want to recommend a good CPU HS/Fan? I'm using the stock one right now, and it's rather inefficient and noisy.



    My HS/fan is Mugen2 purchase from egg , keep my 720x3 @ 240x15 below 40 C @ 100%

    Ohh I'm thinking that your Asus board not do the unlocked 4th core job ... May be I'm wrong.
  21. Quote:
    My HS/fan is Mugen2 purchase from egg , keep my 720x3 @ 240x15 below 40 C @ 100%

    Ohh I'm thinking that your Asus board not do the unlocked 4th core job ... May be I'm wrong.

    I've checked and confirmed that my board (with current BIOS) successfully unlocks all X2 and X3 P2's.
  22. Yea if you cannot get into windows no matter how much voltage you give the CPU then it is a defective core. The tri-cores have a lower unlock rate compared to the x2's. So it is basically a hit or miss....
  23. OvrClkr said:
    Yea if you cannot get into windows no matter how much voltage you give the CPU then it is a defective core. The tri-cores have a lower unlock rate compared to the x2's. So it is basically a hit or miss....


    Unfortunately my local computer shop hasn't had any X2's in stock for a while, so I decided to go with the X3 instead. I did manage to get into Windows a few times, but it always just BSOD'd within 30 seconds with my previously stated message.
  24. Yea, well 3 cores is still the sweet spot for most tasks =)

    I was lucky enough to unlock my x2 550be to an x4 B50 :



    temps are also in the high 20's at idle and low 40's at LOAD.....
  25. Yeah, I'm debating whether or not to buy a 550 and attempt to return it if it doesn't unlock.

    Those are some retarded good temps by the way, at that clock. What cooler are you using?

    EDIT: Nevermind, I found your spec page ^^ Personally, I've been looking at getting the CM V8, looks epic and apparently works relatively well.
  26. Steve_L said:
    Yeah, I'm debating whether or not to buy a 550 and attempt to return it if it doesn't unlock.

    Those are some retarded good temps by the way, at that clock. What cooler are you using?

    EDIT: Nevermind, I found your spec page ^^ I've been looking at getting the CM V8, looks epic.


    Titan Fenir (xmas edition) with MX-2 :




    Temps at 3.8Ghz LOAD :



    Idle :

  27. The V8 is a nice cooler, more on the flashy side... If you have a window it will look great, if not get a 212+ or CCF =)
  28. i have the same mobo and processor and i selected auto under advanced clock calibration and then select enable for the uleash mode and restart with the latest bios i believe its 0605 and walah i got a quad core and it runs stable at 3600 mhz and probly faster also
  29. Im actually running the same board and CPU, luckily mine unlocked just fine. I havent oced yet, waiting on the new case + HSF. I undervolted mine to 1.22v when i unlocked the CPU, but recently had to up it to 1.3v for Mass Effect 2, i kept bsodding for some reason in mass effect 2, but prime ran for 30+ hours without a bsod at 1.22v lol. Sometimes pcs are just finicky if you ask me :P
  30. i just reset my settings to there defaults and ulocked the 4th core its weird being back at 2800mhz. i dont suggest overclocking past 3600 much its pointless if u ask me 800 mhz overclock is enough , i hate how im limited even though i have great cooling and the rest is great 2 ...it should run faster if u ask me.
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