Higher mhz... lower perfomance!?!?

I have a 1.2 tbird with KT7A mobo and 128 MB PC133. I am running my system at 1200 (9.5x133).
I decided to try overclocking my system by raising the mhz in the bios to 1250 (12.5x100). well first surprise is that it posts at 1300 (12.5x104) and second surprise is the performance went down significantly! I'm assuming that lowering my RAMs FSB is the cause.
Is it possible to post at 1250 (12.5x100) and if so, can I set my cpu and RAM to different FSBs??
Thanks in advance!!

Try 9.5x133 or 9.0x133.
Some boards you can set the memory to +pci clk that will run the memory at x100 + the pci bus speed.

The FSB effects the speed that all components of your system run at and reducing this effects everything greatly not just memory, depending upon the quality of your PC133 you may be able to exceed 133 mhz FSB which will improve overall system performance. I run my Duron on Crucial PC133 with a FSB of 140 mhz. It is possible to set the CPU and PCI clock to different speeds on certain mobos on the Abit KT7a it is done with the Dram clock the hclk+pciclk multiplys the FSB with the PCI speed which in this case would be 100 x 33 = 133mhz to use the bandwidth available to the memory however doing this will not overcome the overall performance loss of dropping the FSB from 133 mhz to 100 mhz imho