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AMD Phenom II X2 550 - problem with unlocked cores

Last response: in Overclocking
September 26, 2012 1:43:18 PM

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!
a b à CPUs
a b K Overclocking
September 26, 2012 2:03:03 PM

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.
a b à CPUs
September 26, 2012 2:10:10 PM

Try unlocking one core at a time and see if it works. Sometimes, you just can't unlock them.
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September 27, 2012 6:02:18 AM

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?
a b à CPUs
a b K Overclocking
September 27, 2012 7:09:40 AM

No. If its unstable after being unlocked, its unstable period. Sorry.
September 27, 2012 7:52:05 AM

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?
a b à CPUs
a b K Overclocking
September 27, 2012 8:00:53 AM

SB refers to the motherboard model (southbridge); it's a hardware version number. BIOS updates will not affect it.
a b à CPUs
a b K Overclocking
September 27, 2012 10:08:21 AM

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.
September 27, 2012 10:05:16 PM

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?
a b à CPUs
a b K Overclocking
September 27, 2012 10:07:05 PM

Run memtest86 if you think it could be RAM. If it passes, it may be your motherboard.
September 29, 2012 12:03:17 PM

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.
a b à CPUs
September 29, 2012 12:55:02 PM

You can either unlock the cores and it runs stable, or you can't. Nothing to do with the motherboard.
September 29, 2012 1:01:33 PM

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.
a b à CPUs
a b K Overclocking
September 29, 2012 1:18:04 PM

For CPU cooliing nothing beats the CM EVO 212+, nothing. If your case can fit it that is. For value and cooling.
September 29, 2012 3:39:28 PM

But they stopped selling CM Hyper 212+, right?
September 29, 2012 4:54:29 PM

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?
September 30, 2012 5:33:01 PM

Bump. After updating BIOS, there is no errors - ran Prime95 for 3 hours.

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