Can you do a crossfire/sli whichever you call itwith a regular nvidia geforce gtx 660, and with a gtx 660 ti?
Oh I did not notice that, so your options are to either get a new card and sell your old one or upgrade your PSU. Props to bummermanthat power supply only has two pci-e connectors- I would say , sell the 660 and get one 680 or 7970