Increase RAM with external devices?

It is not possible to connect memory externally. Compared to data storage, memory has to work with a multiple speed to provide your processor with information quickly enough. At such high speeds one moves quickly at the limit of the technical possible. For this reason, in order to be able to run speedily with such speed, the memory must be placed directly next to the processor. A few millimeters can cause considerable power losses as a consequence. Therefore, it is not possible to connect memory externally, since the physical distance to the processor would be far too large. The only way to upgrade the capacity of the memory is to install additional modules (if there are still free slots) or to replace the modules by larger ones.