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  Unlocking phenom 555 on asus m4a7875-m 
 
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Juan Pena Feb 17, 2011, 06:26am EST Reply - Quote - Report Abuse
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Hello to all:

I have this system, runs stable, no problem. Now I came across this news on the net a couple of days ago which explains how this amd phenom II x2 555 is in reality a quad core, just two of the cores are deactivated for whatever reason.

Ok, I googled how to unlock the cpu and I read messages, forums, watched videos on the net. Great.

So of course, it does not work for me. let me explain.

I go into Bios, set ACC to auto and the other option, forgot what it is called, to unleashing. Turn on the machine, biios says four cores activated. Great.

But as Windows starts loading, machine reboots. Continue googling.

Raise vcore to 1.37 and lower multiplier to 14x. Still, machine reboots.

In Bios, I set only three cores activated. Still, reboot.

And here I am, wondering if I have a "lemon".

Any of you who uses this mobo, or has any idea, much appreciated.

Thanks to all in advance, Juan.


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john albrich Feb 17, 2011, 12:46pm EST Reply - Quote - Report Abuse
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Edited: Feb 17, 2011, 01:48pm EST

 
>> Re: Unlocking phenom 555 on asus m4a7875-m

Juan,

Unlocking sometimes requires Windows changes, and even re-installation of Windows in order for the "new" CPU to work properly. Especially if you've already had some BSODs that could have ended up corrupting your OS.

Here are some links that might help illustrate this. I'm not saying they'll fix your problem but will show it's sometimes not just a matter of unlocking the core via a BIOS setting.

http://www.overclock.net/amd-cpus/512232-unlocking-4th-core-in...stion.html
http://forums.overclockers.com.au/showthread.php?p=12595619

I recently ran into the same thing myself on an XP 32bit system I'm experimenting with, I unlocked a core and Windows went all to hell, consistently BSOD on Win32k.sys anywhere from 5 minutes to a couple hours after startup.

Yet, non-Windows self-booting freeware UBCD stress testing of the CPU and RAM would run all the cores for 24 hours without a problem. Which I strongly suggest you use to verify your hardware is stable before taking the time to mess with changing or re-installing Windows. Sometimes a core (or cores) simply won't unlock to a reliable configuration.

Unfortunately, I had to reinstall Windows as nothing else would make Windows work reliably. I suspect that my OS was corrupted at some time and it only made itself evident after unlocking.

Note that the second hyperlink shows that just unlocking the core(s) in BIOS is not necessarily enough. People went through all sorts of contortions to get their unlocked 555 cores to work. They raised the voltage, they underclocked, varied HT link to get a reliable unlocked core. A few posts even mentioned that certain chipset mobos wouldn't reliably unlock 555 cores, but take the CPU to another mobo and it worked fine.


edit:
Found the right hyperlink.

edit to add:
One person even claimed that using a 32bit v 64bit OS can made a difference as well. He couldn't get the 64bit to work, but WinXP 32bit worked OK. Additional physical parts of the CPU die likely come into use when you use the 64bit OS, and those were apparently marginal on the unlocked core(s).

kOrny Feb 17, 2011, 01:41pm EST Reply - Quote - Report Abuse
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>> Re: Unlocking phenom 555 on asus m4a7875-m
I was able to unlock all 4 cores on my Phenom II X2 550 BE with no problems (I did have to update the BIOS beforehand, however).

I did experience some instability when running my memory at 1066MHz though. Runs fine @ 800MHz.

Juan Pena Feb 17, 2011, 08:47pm EST Reply - Quote - Report Abuse
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>> Re: Unlocking phenom 555 on asus m4a7875-m
Thanks for the replies.

I continued tweaking the bios but still, Windows 7 does not boot up. If I boot with only two cores, Windows comes up with no problem.

:(

Unless somebody else has any other idea, I guess i will have to be happy with "just" two cores. Oh well...


Dublin_Gunner Feb 18, 2011, 06:37am EST Reply - Quote - Report Abuse
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>> Re: Unlocking phenom 555 on asus m4a7875-m
Juan Pena said:
Thanks for the replies.

I continued tweaking the bios but still, Windows 7 does not boot up. If I boot with only two cores, Windows comes up with no problem.

:(

Unless somebody else has any other idea, I guess i will have to be happy with "just" two cores. Oh well...




To unlock the cores would not usually require a a re-install of Windows. Its seems as though you have a locked quad, with at least 1 of the 2 locked cores unstable.

Lancool PC K62
Phenom II x3 @ 3.5Ghz
4GB DDR2-800
ASUS GTX570 DirectCU II

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