Date: Friday , August 25, 2017
This Top 5 list is going to be another tough one because many companies have produced excellent and highly influential CPUs in the last few decades. Processors will be judged on several criteria. Among these criteria will be relevance, market lifespan, performance, overclockability, timing, innovation, and anything else that seem pertinent for that particular CPU.
Introduced in 1985, the Intel 80386 DX was revolutionary as it introduced the world to 32-bit computing while retaining backwards compatibility. It was backwards compatible with earlier 16-bit instruction sets used by it's predecessors and offered improved performance and clock speeds over the earlier CPUs. Physical address extensions or PAE were also introduced with these CPUs. This would enable later 32-bit processors to support the feature in some cases and utilize memory beyond the traditional 4GB limit in special cases. Believe it or not, these CPUs were produced until 2007. While their relevance in personal computing came to an end a couple of decades earlier, these CPUs continued to see use in the aerospace industry and even found their way into cell phones. The i386 was offered in clock frequency ranges of between 12MHz and 40MHz. The 32-bit x86 instruction set introduced with the i386, sometimes referred to as "IA-32" or "i386" are still in use to this day.
The Intel Pentium has to be on this list as it showed us what IPC was all about. These CPUs were considerably faster than the i486 processors they replaced. At only 60MHz or 66MHz, the Pentium was as fast or faster than an i486 or AMD 486 CPU at 100MHz. Not only that, but the P5 microarchitecture spawned a very long lived family of processors that dominated the market for several years. P5 microarchitecture based processors were on the market from 1993 to 2001 which is quite an achievement. Although, it's relevance was diminished after 1997 when the Pentium II came out. The Pentium was offered at speeds of 60MHz to 233MHz and up to 300MHz in mobile form. The Pentium name was also introduced over a court ruling during the 486 days that companies couldn't copyright model numbers. As a result, the Pentium became the first Intel processor with a name instead of the traditional model numbers that had been used previously. The Pentium name exists in some for or another to this day. The P5 microarchitecture and indeed it's name are among the most influential in CPU history. The original P5 Pentium would be higher on my list were it not for the FDIV bug.
The original Athlon often gets credit for being the first CPU to best Intel at anything and raced ahead of Intel to the 1GHz mark. While all that is true, I consider the Athlon 64 to be the pinnacle of AMD's achievements when looking at the big picture. The timing of this CPU was also critical to its success as it launched while Intel was pushing it's questionable Netburst architecture. While the Athlon was undoubtedly fast, the Athlon 64 was decisively better than Intel's offerings at all but rendering or encoding tasks. The Athlon 64 is notable for several reasons. It brought the first integrated memory controller to the consumer CPU market. This CPU not only extended the Athlon's lead, but it was actually paired with a solid motherboard platform. Not only that, but the Athlon 64 brought us AMD's x86-64 instruction set which was adopted by Intel and still in use to this day. This is the CPU that provided 64-bit computing to the masses. This CPU in it's Opteron form was also successful in the server market and this remains one of my favorite CPUs of all time.
My number 2 pick for the best CPU of all time had to be none other than the Pentium Pro. This CPU not only had a long life span, but it's P6 Core Microarchitecture is one of the most influential of all time as several of its design elements would be featured in CPUs through the Core 2 Duo. The Pentium Pro was an incredible achievement and offered performance far ahead of the standard Pentium in 32-bit applications. These CPUs were the very definition of "reliable" as it operated in servers well past its expected lifespan. I ran two of these on an Intel PR440FX Providence Motherboard myself. The overclocked CPUs of mine still function to this day. Strangely, despite its professional and heavy corporate use, it was a beautiful and striking CPU. It had an attractive heat spreader design and large and unique, rectangular package. It's pins were split into a low density and a high density section which was also unique at the time. These CPUs came in various flavors between 150MHz and 200MHz as well as a variety of cache sizes. It's successor, the Pentium II was actually slower than the Pentium Pro due to having half-speed cache on a clock for clock basis.
The Pentium Pro was also used as the basis of several supercomputers, including the famous ASCI Red, the first computer to reach the teraFLOPS threshold in performance. Many of our readers have even noted the Threadripper's rectangular package as being reminiscent of the Pentium Pro, proving that while these CPUs are gone, they are surely not forgotten.
The Intel Core i7-2600K makes the top of the list for a few reasons. It was probably the last large leap forward we've seen in a single CPU generation from Intel. Intel's had bigger jumps, but it's been virtually stagnant since the introduction of its Sandy Bridge CPUs. More importantly, the Sandy Bridge CPUs (more specifically, the Core i7 2600K) are still relevant today despite being over 6 years old. It's platform is dated but when paired with a modern GPU it's continued to remain relevant as a gaming platform. Many of our readers still use these aging systems every day and push them hard with no signs of stopping anytime soon. Many of these have been replaced due to failing motherboards rather than a desire to upgrade. Sandy Bridge CPus could often be overclocked well north of 4.8GHz and few Intel CPUs have been able to achieve those same speeds. Many subsequent CPUs Intel has released has for the most part lost a couple hundred megahertz of overclocking headroom compared to Sandy Bridge. The miniscule IPC improvements we've seen each generation have failed to close the clock speed gap and thus, provide little benefit to upgrading in the gaming realm. It's for its continued relevance, influence over modern CPUs, and popularity that this CPU is #1 on our list.
All of the CPUs on this list are ones that were not only good overclockers, and somewhat of a value, but highly influential CPUs in their own right. These set the bar for how we judge value in overclocking and are shining examples of what performance, after a little tuning, looks like. Many of these CPUs were relevant far past the manufacturers' intended lifecycles and powered many gaming rigs and personal workstations for many years. CPUs like the Core i7-2600K and the Core i7-980X power many gaming rigs to this day. Equipped with modern graphics cards, these outstanding CPUs will continue to do so for some time to come. That said, the CPU market is heating up again and we may have a very different list if we revisit this topic in a year or so. Only time will tell.
Editor's Note: Worth mentioning before you start commenting, we do have "The Best Overclocking CPUs of All Time" coming up next.