(1) See
white box testing and
white box networking.
(2) A PC made from commonly available parts. White box marketing refers to the many small companies that assemble and sell Windows PCs (and occasionally Linux PCs) under their own brand name (or no name). These companies often take advantage of surplus motherboards, drives and other parts they can easily mix and match.
Mostly White
The "white" refers to the packing carton of the computer case, which is often white. More importantly, the carton and case are devoid of the original manufacturer's logos so that resellers can add their own if they desire.
In Decline
Due to sales of laptop and tablets, the desktop market is in decline, which also affects the white box market. Although there is a "white book" market for white box laptops, parts are not as interchangeable as desktops, and they are more difficult to support. Both the white box and white book markets are expected to continue declining. See
OEM.