I just recently bought a new computer from components and built it myself. It's been running stable, so I decided to try overclocking and playing around with settings in general to try and increase performance (not that there's been any problems thus far). I have a Phenom II x4 965 Black Edition processor and an ASUS M4A87TD motherboard - I can post any other system stats if needed.
The first thing I did was flip the Core Unlocker switch on my mobo (shut down, w/ power off) and when first booting, it showed in the initial boot screen that 4 cores were operating. When it got to the point where it usually starts to load up Win7 Home Premium 64, the screen went black and hung - not a monitor problem, and not a graphics card problem so far as I could tell. The computer did not progress any further in startup from this point.
I shut everything down, did a new cold boot, and this time the initial boot screen displayed that 3 cores were operating. Win7 started up fine and everything seems to be running without hiccups - tried a few games, etc. I can't say I noticed any overall change or increase in performance, but my main concern right now is the number of cores reporting as operating.
I shut everything down through Win7, turned off power to the system, returned the mobo Core Unlocker switch to default and then flipped it back to "unlock" again. Booting up this time, again no problems, but it still shows 3 cores as operating. From reading through a few posts here, I checked the Device Manager, and that also only shows 3 "cores" as operating in the Processor subcategory.
Do I have a defective CPU after all this? Is it a limitation of the mobo or something else that this is the "best" I can get? Am I missing something blindingly obvious? Any help would be appreciated!
I should add that I am completely new to this sort of thing, upgrading from a 10 y/o computer and putting out the money for a "quality" system that I assembled myself this time. The computer went together with but a single easily-solved hitch, and this is the first stab I've taken at playing with BIOS or settings or anything with a computer, short of upgrading memory, PSU, etc. on my old one.
[Edit] Oh, and the CPU temp. seems to be sitting at around 36*° C and the mobo at 31° C. It's also running w/ a 750W Corsair PSU, dunno if that's important? [/Edit]