ok, i've got an athlon 900 at 1066 stable right now. it runs 43 deg C with no load and 48 deg C with full load. i've got an abit kt7a-raid with crucial cas2 ram. the important settings are 133 x 8 and voltage of 1.85. i had to get as much cooling as possible, including:
1) copper hedgehog with sunon 5200 rpm fan (didn't opt for the delta 6200 rpm fan--plycon said that the fan draws blood if you touch it)
2) arctic silver II thermal compound
3) front and rear case fans
4) antec hard drive fan and fan card
edit (forgot this):
5) all rounded cables: IDE, SCSI, and floppy
the rounded cables help with air flow. got all the stuff at plycon. really good guys, reasonable shipping costs, takes paypal, no sales tax for CA res (they're in GA), and lots of neat stuff. here is a link:
Plycon. you can also round your own cables too, but i opted for machined stuff.
it tried the multiplier at 8.5 and it won't go there at 133. some other info: this processor is actually the retail version and is a purple die. shouldn't make a difference, but i mention it.