Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_80 (pci_express VARCHAR, memory VARCHAR, model VARCHAR)

### Question ###
What is the PCI-express with a ddr2 memory and a nforce 520 model?

### Accurate SQL ###

SELECT pci_express FROM table_name_80 WHERE memory = "ddr2" AND model = "nforce 520"