Some of the companies' servers (e.g. Dell) can boot pretty fast in these days. If you want see something that boots slowly, try an IBM HS22 blade (3+ minutes self-initialization after insert, 2.5+ minutes to pass initial BIOS screen to storage initialization and boot-start).

IBM's QPI-linked dual servers boots even slower as one technician explained to me. Presumably you can make coffee during the wait.