I've had a lot of trouble with the 4th core being utterly unstable on my PII 710. I decided to grab an after market CPU cooler (Arctic Cooling Freezer Pro 92mm) and some AS5 because my room temperature is quite mild and my stock AMD fan was flat ass too loud and annoying. A quick test of the temp difference showed a 14C decrease in temperature. I was ecstatic, so I went back to the unlock 4th core thread for my motherboard and voila! It worked like a charm first try!
Core Temp is apparently having a little issue figuring out what my temperatures are. So what are some other programs I can use to monitor temps? I would use AMD Overdrive but I don't have a BE CPU.
But yeah... This could be a complete coincidence, but it worked enough for me to believe that I was just having a terrible heating issue when the 4th core was enabled. For those of you having a similar problem, go out and grab a decent CPU cooler and give it a shot. I paid $27 for this cooler over at Newegg and it does the trick and many more.
AMD overdrive doesn't require a BE processor, and it can be useful as a system monitoring program and even stress tester if you aren't using it to overclock.
Not being able to read core temps is a known problem with unlocked processors, I'm amazed you haven't already read about it. I wouldn't imagine they are more than a few C over what they are when running as an X3.
With my 720 BE, I first monitored the temps before unlocking to note what the core CPU temp was compared to the overall CPU temp. I saw a 10° to 15° degree difference where the CPU core temp was lower.
So, when I unlocked my 4th core, the overall CPU temp went up about 3° so I knew what the actual core CPU temp was.
With my cooler and overclocking, I get around 32°C idle and 45°C fully loaded. With Prime95, it got to about 55°C tops (the overall CPU temp listed 65°C).
My 710 when unlocked read as a TWKR chip in CPUID, but I couldn't validate because it wasn't a current version at the time (installed off a 9month old backup Apps disc) and when it was updated, didn't give me the TWKR label. Was saddened by that, hah.