Ok..I found the thread that changed my mind on getting a Tbird.
I cut and pasted it for you..so here you go---
"i have a Slot A Tbird 700 that i might be able to let go for the right price. I'm using it on an ABIT KA7 with a gold finger device overclocked to 800, but i'm pretty sure i would get to 900 with out problems since the person i bought it from was able to do that with the old 750 chipset by athlon. but i can't hit past 800 because of the KX133 limitations on TBirds 800+ "
You see you were using an old 750 chipset with that K7M, that is why you were able to get above 850...but as the seller told me, the KX133 boards, which is what the Epox board is, have some kind of limitation with Tbirds.
That is why I stayed with the classic athlon. Here is a shot in the dark, look to see if there is a new bios from EPOX addresses that problem..I doubt it, but worth a try.