The new AMD Athlon 64 X2 5000+ processors offer a lot of fun for overclockers, according to Nordic Hardware. They heard a Chinese overclocked managed to get the chip from 2.6GHz to more than 3.5GHz without the use of any exotic cooling.
With an unlocked multiplier and cherry-picked cores it should prove be a good overclocker and it really seems like it is. Chinese overclocker druid-su has managed to push his sample to 3520 MHz, simply by bumping the multiplier up to 16x and raising the bus slightly to 220 MHz. He used an ASUS M2N32-SLi Deluxe based on the nForce 590 chipset to do so. A rather high frequency for a K8 processor if you don't use more exotic cooling like phase-change compressor coolers, dry ice or liquid nitrogen.