CREATE TABLE table_name_80 (pci_express VARCHAR, memory VARCHAR, model VARCHAR)

What is the PCI-express with a ddr2 memory and a nforce 520 model?
SELECT pci_express FROM table_name_80 WHERE memory = "ddr2" AND model = "nforce 520"
SELECT "pci_express" FROM "table_name_80" WHERE "ddr2" = "memory" AND "model" = "nforce 520"