How to create clustered index on a table which has all duplicate columns

Hi, I have a table which has good amount of data about 8 million records in it, but all the columns in it are with duplicate values. Now, i have created the non clustered indexes on some of the columns, but i read somewhere that using all non clustered indexes on a table can affect the CPU performance issues. How can I create the clustered index on this table now? Can anyone suggest on this?