Are the cpu's you have 1.2 or 1.1 T-birds ? Some of the 1.2 Gb T-birds have 1.3 cores, according to posts here and there these are red and do exactly that, when the multiplier is set at 12.5 they add about 5 fsb to get to 1.3 GHz. Probably an AMD little trick to avoid increasing the multiplier. The 1.3 T-birds are not out yet so it is probably a nice way to test the manufacturing process and maybe start stocking up the 'good' cpu's while relegating the 'bad' ones to 1.2, although this is speculation. The same may be occuring with some 1.1 T-birds. Any T-bird lower than 1.1 GHz shouldn't have the ability to do the above.