Another way to overcome the limited options available to laptops is to make use of the ExpressCard slot built into many laptops to drive an external graphics card, or GPU. This is typically achieved using an external PCI-E enclosure connected to the laptop using an ExpressCard adapter. A desktop-based PCI-E graphics card is then physically installed into the enclosure, where it communicates with the laptop at the full 2.5Gbit/sec throughput specified in ExpressCard 1.0 or 5.0Gbit/sec for ExpressCard 2.0. Solutions that leverage the higher 10Gbit/sec in Thunderbolt has also started to appear, though they pertain only to Mac laptops for now-PC laptops with Thunderbolt ports have yet to arrive at the time of this writing.
As you can imagine, setting up a PCI-E expansion chassis and installing a PCI-E graphics card is a significantly more involved process. In the context of deploying multiple monitors with a laptop, existing device drivers may also not play well with those needed for the external GPUs. And while the ExpressCard standard calls for the capability to perform a hot-swap, device drivers often behave unpredictably when cards are swapped in or out, necessitating a system shutdown prior to the insertion or removal of the ExpressCard adapter.
Magma is one vendor that makes a range of PCI Express expansion chassis that connects to laptops using an ExpressCard adapter, with support for enclosures that can hold up to 16 PCI-E expansion cards. Village Instruments also sell a range of PCI Express docks created with an emphasis on getting getting graphics card to work with laptops equipped with ExpressCard slots, while Sonnet is already shipping the Echo Express Thunderbolt Expansion Chassis.
6. Software Approach
If nothing else, you can use software to chain old laptops or computer systems together in order to use multiple displays as part of a single system. One such application is MaxiVista Multi Monitor Software, which has a client component that installs on PC laptops, desktops or even the Mac. Though it works reasonably well over a fast LAN, the main workstation must be a Windows machine, and there are restrictions on how monitors may be arranged. Moreover, client laptops or PCs must be kept powered up, which represents an additional cost due to their electrical consumption.