Years ago when Intel was still wild about the NetBurst architecture the company announced BTX, a new form factor to replace the old ATX form factor.
However, BTX didn't become as popular as Intel hoped and the chip giant is now de-emphasising its BTX plans.
BTX was considered necessary by Intel because then it had plans to take the Pentium 4 and its Netburst technology to GHz beyond the dreams of Doctor Spinola. The engineers designing chassis had to puff and blow to ensure the design was such that it could accommodate the heat expected to be generated by such monsters.
Intel is saying that the BTX design is useful for servers now, but there was a time when it was confidently predicting it would dominate the desktop, too.