A decade ago, server hardware CPU choices were limited – for the most part – to a few core architectures running a narrow selection of highly proprietary operating systems. Sun SPARC chipsets designed for the Solaris UNIX operating system were extremely popular in the financial and upstart dot-com environments, whereas Intel CPUs for Microsoft Windows environments were the choice of the corporate desktop environment. HP, IBM, and Digital made their own proprietary CPUs to accompany their own operating systems.
To give you an idea of how long ago that seems now, Apple was a total non-factor in server systems and was nearly absent from desktop environment discussions as well (Apple’s mobile device introduced in 1998 was known as the Newton and soon disappeared from the market). Multiple tidal waves of change have washed over the hosting industry in the past decade, with possibly the most monumental of those being the rise of open source operating systems, based on Linux. The popularity of Linux quickly dwarfed the proprietary UNIX variants (HP-UX, Solaris, AIX, etc.) to the point where today many of those operating systems that still survived actually have open sourced themselves and include large chunks of the Linux core themselves.
Because it was designed from the outset to be modular and cross-platform, Linux distributions became popular on a number of chipsets, including SPARC and Intel chips. At that point, it became a battle of price-performance and for most business users, the Intel platform became the one of choice…although no longer necessarily for “Wintel” (Windows/Intel) only. Today, when selecting a hosting provider, both Wintel and “Lintel” (Linux OS on Intel CPU chipset) are both very popular options.
The most popular Intel server CPU today is the Intel Xeon (http://www.intel.com/p/en_US/products/server/processor) which, at the time, of this writing come in the 5600, 6500, and 7500 series. The Xeon CPU line was introduced in 1999 with the Pentium II Xeon chip and subsequent releases dropped the Pentium brand-name from the line. Today, the Xeon CPU comes in both 32-bit and 64-bit architectures and can also include single, dual, or quad-core configurations. In CPU terminology a “core” represents one processing unit within a chip with the term “quad” meaning there are four of them (as opposed to the old single-core days). Intel Xeon CPUs released in 2009 and later (such as the 7400 “Dunnington” chip and the 7500 “Beckton” chip) are multi-core chips capable of supporting up to eight cores and up to 24MB Level 3 cache on-chip. The primary competitor to Intel in the area of server CPUs is the AMD Opteron series. AMD Opteron CPUs also come in a variety of multi-core options, up to the 12-core 6100 series CPU released in 2010. The Opteron CPUs gained an early technical lead over the Xeon CPUs because they were able to outperform Xeons in the execution of x86 32-bit apps (early Xeon chips suffered noticeable performance degradation when executing x86 32-bit apps).
When focusing in on a CPU, it is important to not view the chipset as the single determinant of system performance. In many heavy data write environments, hard drive speed and disk access times can drastically affect perceived system throughput. Network access and overall server load are obviously performance determinants as well. At the end of the day, the actual server software design and implementation may have a larger positive/negative affect on performance than any of the modern CPUs or hard drive options. Experienced developers have all seen more than their fair share of applications brought to their knees by poorly designed database SQL queries, for example. Therefore, be sure to focus on your overall system design when designing out your computing environment.