Last I heard, no one has been very successful with any of the KK266 series motherobards, not with CPU's newer than Palomino. I think I recall something about capacitor replacements being needed to make even Palominos to work reliably.
I think the following thread encapsulates the KK266 story.
<A HREF="http://forums.pcper.com/showthread.php?t=247250&highlight=kk266" target="_new">http://forums.pcper.com/showthread.php?t=247250&highlight=kk266</A>
I'm not sure why some socket A motherboards have so much trouble while other don't.
I don't have an Iwill mobo but I do have another KT133A mobo, an Epox EP-8KTA3PRO. At one time or other installed in this motherboard I've had a Duron 600 (Spitfire), a 600 @1112 Mhz, A Thunderbird @1.5 Ghz (and up to 1.6 Ghz), a Tbred B XP1700+ at stock 1.466 Ghz, overclocked @1.875 Ghz, and a mod'd XP1700+ running at 2.1 Ghz.
That very same mod'd CPU I've also installed in a really old Abit KT7 (no A) and ran it up to 2 Ghz (but at 20 x 100).
I learned a lot getting those upgrades and overclocks to work but not enough to explain why similar upgrades don't work in the Iwill mobos.
I suggest you check the other posts in the Iwill forum at <A HREF="http://www.pcper.com" target="_new">http://www.pcper.com</A>. (formerly AMDMB.com but no longer AMD only). There may have been developments for the KK266 of which I am not aware.
<b>A mind is a terrible thing</b>