MicroAMD2k1,
Like what the others said here, Vcore should solve that problem.
On the Iwill KK266 mobos, I believe they are maxed out@ 1.85V manual. Try 1.85V and see if it works. If not, you might need more voltage. In that case, you'll have to Volt mod your chip. I haven't done it on the Athlon T-bird yet.