While Advanced Micro Devices and Intel Corporation do not have a lot in common when it comes to central processing units' micro-architecture these days, both firms engage some very close approaches to enhance their x86 processors with 64-bit capabilities. For a number of years Intel has been making tremendous efforts to penetrate high-end enterprise server market with its Itanium processor, a chip designed from the ground-up with no x86 in mind. The CPU may be considered as a pretty successful nowadays, but what Intel cannot address with it and its EPIC architecture is the volume market of web, small database servers and other applications of the same kind. The obvious problem Itanium-based servers have besides the cost is very low performance in x86 applications – the most wide-spread software in the world – what requires deploying new IA64-compatible programs making a transition to Itanium an extremely expensive task. If the transition is to costly foe large companies, there probably no ways for technology to be adopted by masses.
Advanced Micro Devices decided go another route. Historically the company could not compete with Intel for lucrative markets of high-end desktop and workstations machines, not talking about enterprise-class servers. It is pretty obvious that AMD could not afford to develop a processor incompatible with existing software infrastructure; consequently, AMD developed an x86 architecture that contained 64-bit extensions and numerous other performance tweaks. The results are AMD Opteron and AMD Athlon 64 microprocessors that form the only family of 64-bit processors able to serve various market segments from desktop to enterprise server.
News source: X-bit labs