The X series was developed as a direct successor of the discontinued 500 series.
One noticeable change was the addition of a fan to every X series model, compared to some models of the 500 series, which did not include a fan. Apart from that, two models of the X series were built with an internal optical drive. This was an odd departure from the usual norm of every X series model, which never included an internal optical drive.
This category has the following 55 subcategories, out of 55 total.