Table schema:
CREATE TABLE table_name_11 (pci_express VARCHAR, memory VARCHAR, sound VARCHAR)

Question: Which PCI-Express has a DDR 266/333/400 Registered/ECC memory and Enhanced AC'97 2.3 sound?
SQL: SELECT pci_express FROM table_name_11 WHERE memory = "ddr 266/333/400 registered/ecc" AND sound = "enhanced ac'97 2.3"