用一段來說明,
事實上在這方面 intel 早就有在研究,
只不過他門當初沒有決定要用這個架構,
而且 X86 本身就是 Intel 設計的.

所以在技術上其實根本就不見得有追不追上的問題.

"History of Intel 64

Historically, AMD has developed and produced processors patterned after Intel's original designs, but with x86-64, roles were reversed: Intel found itself in the position of adopting the architecture which AMD had created as an extension to Intel's own x86 processor line.

Intel's project was originally codenamed Yamhill (after the Yamhill River in Oregon's Willamette Valley). After several years of denying its existence, Intel announced at the February 2004 IDF that the project was indeed underway. Intel's chairman at the time, Craig Barrett, admitted that this was one of their worst kept secrets.[6][7]

Intel's name for this technology has changed several times. The name used at the IDF was CT (presumably for Clackamas Technology, another codename from an Oregon river); within weeks they began referring to it as IA-32e (for IA-32 extensions) and in March 2004 unveiled the "official" name EM64T (Extended Memory 64 Technology). In late 2006 Intel began instead using the name Intel 64 for its implementation, paralleling AMD's use of the name AMD64"
(http://en.wikipedia.org/wiki/X86-64)