Similar to the Thunderbolt IC we found in the MacBook Pro 15" Unibody Early 2011, the iMac Intel 21.5" EMC 2428 features the Intel L102IA84 EFL Thunderbolt port IC.

Thunderbolt claims to provide 10 Gbps throughput for both input and output. It appears that both PCI Express and DisplayPort receive their own 10 Gbps data channel. That's nice, as you don't want your display competing with your external hard drive for bandwidth.