Ulbricht's Samsung 700Z laptop used DDR3 RAM. These guys couldn't reproduce the "cold boot"/"RAM freeze" attack using DDR3 RAM: http://www1.cs.fau.de/filepool/projects/coldboot/fares_coldb...

But I don't see why they would need to freeze anything. I would think the feds should be able to make a device that plugs onto the DRAM connectors of chips and reads the content, although I'm not sure.