I have a Phenom II 550 which i can unlock to 3 or 4 cores and successfully boot into windows... However, in some apps and games the PC will hard lock when i have 4 cores active, so its not 100% stable....when 3 cores are active i have no such problem, the PC is 100% stable with everything up to 3.85Gz, which is how i run my CPU, 3 cores @3.4Ghz. I simply got used to the idea of Core 4 being a dud and moved on, however Gigabyte has released a new BIOS update which allows you to turn on or off the 2 extra cores individually... Ie.. Cores 0,1,2 or Cores 0,1,3.... The strange thing is, whichever config i use the PC is 100% stable with 3 cores, which suggests that all 4 cores are 100% stable... Except that when i run all 4 cores together, the same hard lock problem occurs.... How can i have a CPU that has 4 good cores, but i can only run a maximum of 3 with 100% stability... I have tried everything i can think of, upping CPU vlts to 1.55, raising & lowering NB speeds and vlts, lowering the HT speed...all without success. My DDR2 is at stock speeds and vlts... Anyone got any ideas how 4 good cores are unstable when run together but 100% stable when run separately?
some guys on xtreme systems had the same experience.. http://www.xtremesystems.org/forums/showthread.php?t=233035
I might be wrong about this but i think 1 of the cores is not quite as good as the rest and because of the overclocking the mobo is sorting out the best 3 to load up, when you ask it for a bit more thats when it's locking up.. try running the stock frequency and bring it up slowly to see where it all goes wrong, this will help establish the limits of the cpu if what i've said is the case, running prime 95 will load all the cores so if 1 is a dud it'll show it up pretty quickly...what i do know for a fact is sometimes there's only 1 good core and this is what you might have..Still 3 for the price of 2 and a decent overclock is better than a slap in the face with a wet fish
I wish it were as simple as running things at stock speed, but the hard lock will occur whatever the clock speed, i've been as low as 2.6Ghz on stock vlts...so its not that. Dont get me wrong, im more than happy with a CPU that gives 3 cores @3.85Ghz.......it can handle anything i throw at it. Its really just a question of trying to figure out what could be causing the issue, rather than any greedy desire to get a 4th core for free.
thanks for that link.... Exactly the same problem as i have but, and this is the important thing, on an ASUS Mobo.... That proves its definitely a problem with the CPU itself, rather than any BIOS or Mobo instability..peculiar to my Gigabyte setup. At one time i thought changing the Mobo would solve the problem, obviously not.
looks like you have 1 good one and a dud, it's just pot luck if you get 1 with 2 disabled working cores thats why AMD turn those into dual and tri cores because it saves them money not having to bin any cpu's
Couldn't be something a bit 'left field', such as the TDP of the CPU couldn't meet the required levels? Likewise, the issue could be in the power delivery circuits on the chip? Maybe loading up the processor with a full quad core load 'puts it over the edge'? Cheers, SouperAndy
