it's most likely this simple...
when you increase your fsb, it also increase your pci bus speeds. at a 100mhz fsb, your pci slots are running at 33mhz (100/3), which is what they're meant to. when you bump the fsb up to 114, your pci slots are now at 38mhz (114/3)and pci cards are simply not meant to run at anything higher than 33mhz, but most will to a degree. you simply reached the limit of your sound card.
to get over this, try changing your multiplier on your cpu rather than just push the fsb higher.