The UCF for the 3S1200EFG400 device provided with the PCI LogiCORE v3.155, currently available through CORE Generator, is not meeting timing using 8.1i Service Pack 2.
To resolve this issue, please download new UCF files from the following locations:
These downloads contain 32-bit and 64-bit UCF files to replace those provided for the 3S1200EFG400 by CORE Generator. Please use these UCF files instead of the ones delivered with CORE Generator. These files will be incorporated into the next official PCI CORE Generator release.
If timing errors persist after downloading these new UCF files, please see (Xilinx Answer 22589) for more information on targeting Spartan-3E devices.