I would check the FSB setting in your bios. By default the 2100+ should run at 266 MHz (alternatively shown as 133 MHz in most bioss). The speed that you said your processor is now running at 2000+ at 1.3 GHz is quite interesting indeed considering that the default speed of the 2000+ is 1.67 GHz. Whats even more interesting is how your processor speed dropped when you formatted your hard drive. Did you at all change any settings in the bios just before you formatted or after you formatted your hard drive? Or have you reset the CMOS?