I'd have to suggests trying SETI or FOLDING. They are just solid and more consistent. Just run them for an hour or so, if it crashes you have a problem and will have to decrease your mult a bit then try to burn. When you find that stable sweetspot just burn baby burn burn burn burn till you lose 4 layers of skin, believe it or not, I get that on a hot summer day on the beach! (Burn for a few days 24/7 then try to up the mult a bit, then burn again till you hit the top) Don't use a high fsb by the way because you don't want to test your system jsut you cpu core. High fsbs may cause freezes due to otehr things such as PCI, memory, etc... (use 133x10.5)
By the way, your best geuss is to use MBM5 if you don't want to buy an accurete external them. I wouldn't with those temps because MBM5 won't be off by more than 1-2 degrees tops and you'd be safe with those temps. I would guess your full load temps to be around 40-45C with MBM5 which is great, try that, I'm interested to know, dont use the asus probe, it is very misleading! But if MBM says 45 on full load, it is most likely the real actual temp is not more than 46 or 47 which is defently ok. Only get an accurete tehm if you are ranging around 55C.
have fun,
trainTuTu