I've got a Duron 800 that I purchased from OCZ preoverclocked and supposedly tested stable at 1100mhz.. however, I can only run this box stable at 950. 9x multiplier and 105 fsb. At anything past 1ghz, it acts a little strange and crashes fairly frequently, and I'm pretty sure it's not a cooling problem. It does make a pretty big jump between idle and full load temps though... as in 32C idle up to 50C at full load. The heatsink is lapped though, and I've got a crapload of fans. Ah well.. but yeah, you should be able to crack 1ghz with your duron if its even halfway decent. (unlike mine apparently)