My retail PIII_650E FC-PGA does 975 stable (150 FSB) on my Abit SE6 board. I can only use one DIMM (even at stock 100Mhz FSB), which I think is related to the fact that I'm using ECC RAM, which has two extra chips to power and is probably overloading the RAM bus.
Still, 975 stable in games is nothing to sneeze at. I'll be getting another DIMM for it, non ECC, to see how it does.
Oh, it's Alpha'ed, of course, and running at Vcore of 1.8v. Stays in the mid 30's to low 40's C range.
Just my $0.02