Why are there two sizes of ExpressCard modules? Is there a performance difference between the two?
There is no direct performance difference between an ExpressCard/34 and an ExpressCard/54 module. In fact, both modules use the same 26 contact connector, so your computer is not even aware of which size of module has been inserted. Both sizes of module are able to take full advantage of the features of the PCI Express or USB 2.0 interfaces. However, the ExpressCard/54 form-factor does allow for greater thermal dissipation due to its larger surface area. This means that applications that run “hot”, such as high-speed data transfer, may be designed into an ExpressCard/54 module to take advantage of the greater thermal dissipation. Because performance does not vary with module size, module developers always prefer to fit their applications into the smaller ExpressCard/34 form factor when possible, but there are some applications that require the larger ExpressCard/54 module’s extra width. Some examples of this are: SmartCard readers, CompactFlash readers, and hard drives with 1.8″ platte
