You need to change the FSB which is the 133 number. The multiplier the 13.5 you write about is locked by the cpu, so even if you do change it it will stay at its default of 12.5 or wateva it is. You need to raise the fsb in small increments ie to 135, 137 etc etc. As you do this you will find the machine becomes unstable, you then need to apply more voltage to the cpu etc. Look around on the net for guides there is loadsa information around on it. The best amd chips at the present time for ocing are the 1700+ and the 2100+. I currently have my barton 1.83g running at 215fsb for a total of 2480mhz. A nice 650mhz for nothing.

Good luck matey

Well I have a 2100+ and I don't know how to overclock it nor if I risk a lot nor what cooling to get (i have stock cooling, and not lots of cash)

Ok, so I will start adding FSB slowly, and when it becomes unstable, increase voltage, great! Maybe I won't have to buy a new CPU afterall, at least this summer

Right now: 1.67@1.68GHz

Please keep posting tips, links etc :)