Supposedly these don't have a bridge since they crossfire thru the mobo. But yes, according the previous charts, they were compatible. Unfortunately, AMD updated the chart recently to include the newer cards and they don't show the old ones anymore.
Be that as it may, I just gave up and decided to sell the (2) practically new cards (it's on Amazon at the moment for cheap) and buy a AMD Radeon HD 7750. (recommended buy from Tom's!). =)