AMD Phenom II X2 550 - problem with unlocked cores

Hi everyone,


My rig:

Processor: AMD Phenom II X2 550 (not BE)
Motherboard: Gigabyte MA770-UD3
Graphics card: Gigabyte Geforce 275
Hard drive: Seagate Barracuda 7200.12 - 500 GB
RAM: Kingston HyperX DDR2 4GB


That's what I did: set [EC Firmware Selection] t [Hybrid] and [Advanced Clock Calibration] to [Auto]. I could see in system specs AMD Phenom II X4 B50, but system was buggy. So I wanted to change DCTS Mode to [Unganged], but it was set already, so I changed it to [ganged], and problems seemed the same. So i ultimately changed DCTS Mode to [unganged] and set SB750 Spread Spectrum to [enabled] and set CPU's voltage to 1.4250. System was pretty stable, but errors with the graphics driver occured (temporary black screens - driver failure).

So i turned off [Onboard 1394] and [Drive A], and then applied only one extra core, and it was as bad as with the 4 cores. So i replaced this core with other one and now system works without problems, but in Prime95 error occurs after about 8 minutes. 3DMark 06 runs fine and I get higher results than before unlocking.

What should I do now to make it more stable? I heard something of updating BIOS and change the numbers in ACC (right now they are seto to -2%). Is it possible to make this CPU work on 4 cores, or it's just a dream?

Thanks in advance!
17 answers Last reply
More about phenom problem unlocked cores
  1. Unfortunately there is no gaurantee youll get to unlock either core and have it be stable. They are turned off for a reason. My GF has a 550 CPU BE and I unlocked both without issue. Some will work with 3 some will work with 4 some will only work with 2. You got one with 2 bad cores im guessing.
  2. Try unlocking one core at a time and see if it works. Sometimes, you just can't unlock them.
  3. Well, computer runs fine with one core unlocked. Fourth one was giving artifacts. On the outside everything runs fine, but I can see unstability in games and it gives errors after a few minutes in Prime95. Can I make it more stable?
  4. No. If its unstable after being unlocked, its unstable period. Sorry.
  5. Too bad :/

    I noticed that Spread Spectrum option has number SB700 instead of SB750. Does it mean I have older BIOS or rev. of mobo?

    I did all the unlocking at the stock cooling system, which is very weak (about 60 celciuses in-game on stock settings), so after increasing voltage I'm guessing temperature jumped sky-high. Could it affect the core into unstability of some kind?
  6. SB refers to the motherboard model (southbridge); it's a hardware version number. BIOS updates will not affect it.
  7. You are spending an awful lot of time troubleshooting an issue which doesnt exist. You tried to unlock the 2 cores, they are both unstable. Stop unlocking them and the problem will go away.
  8. Well, there is an issue, because Prime95 gives errors without unlocking cores as well. Now I can't say it's stable for sure, but I've been running my rig this way for about 2 years.

    The story is, that I had the same problem with Phenom II X2 550 BE, and I got it replaced by the terms of warranty and they gave me an ordinary model without BE instead. Anyways, both CPU's kept giving me errors in Prime95 and I stopped fighting with warranty, because everything seemed fine.

    Also, I have been experiencing stutters - problem posted here.

    To sum up, something must be wrong with the motherboard or RAMs.

    Any suggestions?
  9. Run memtest86 if you think it could be RAM. If it passes, it may be your motherboard.
  10. Ran memtest86+ for 9 hours - no errors reported. That leaves me with broken mobo? I'm planning to switch anyway, regardless for the errors.

    I have already 4GB of DDR3 RAM's and they are waiting to be used. Which AM3 motherboard would you recommend for me, that could give me a fair chance of at least unlocking this third core? I know that it may be impossible after what I've seen already after unlocking, but it's worth trying if it wont cost me more. I mean here something not so expensive, so it narrows down models for sure.

    PS. After OC'ing CPU to 3,7 and increasing voltages, I got BSOD after playing Skyrim for some time. Propably temperatures were way to high, but I'll invest some money into SilentiumPC Spartan PRO HE924. It's not a beast in cooling, but still tops the others in value/quality segment.
  11. You can either unlock the cores and it runs stable, or you can't. Nothing to do with the motherboard.
  12. Then forget about unlocking cores. I just need to find a new AM3 motherboard for DDR3 RAM's that would eliminate issues that are within the current one.
  13. For CPU cooliing nothing beats the CM EVO 212+, nothing. If your case can fit it that is. For value and cooling.
  14. But they stopped selling CM Hyper 212+, right?
  15. macors said:
    But they stopped selling CM Hyper 212+, right?


    http://www.newegg.com/Product/Product.aspx?Item=N82E16835103099
  16. EVO is newer model - more expensive, with a little better cooling. Too bad that in Poland, it costs 2 times more than Spartan PRO.

    Any suggestions about motherboard?
  17. Bump. After updating BIOS, there is no errors - ran Prime95 for 3 hours.

    As for the motherboard - I chose MSI 970A-G46.
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