You raise the FSB to overclock, but this requires good ram, mobo and power supply.
And a 3200+ is not guarnteed to run at 3500+ speeds, it's just likely.
All the CPU's start off the same (for the core) Than they get tested at a speed and if it passes, it will say lets go into the 3500+ bin. If another CPU doesnt pass 3500+ speeds, it goes into the 3200+ bin.
But since AMD owns soo much, all their CPU's go into the 3500+ bin for the main part, so they do a little switch and put them in the 3200+ bin, same for intel (on a lesser scale)
And because AMD still owns, you can overclock it even higher than a 3500+