pci express ac coupling

Hi all

Does anyone know whether the ac coupling caps for PCIExpress should be located at the gold fingers or at the bridge chip. I have a layout in front of me and putting the caps next to the gold fingers would make the discontinuity just a little bit bigger, but putting them next to the bga adds another seperate discontinuity. The only advice that I've found says that they should go at the bridge but doesn't say why.

Any pointers appreciated.

Colin