100MHz Bus Speed & Socket-7 Motherboardsby Anand Lal Shimpi on September 27, 1997 6:46 PM EST
- Posted in
For years our processors had been crippled by a major factor which had remained overlooked, not the clock speed at which the processors ran at, but the speed at which the rest of the system could transmit data, commonly known as the Bus Speed.
Now used as a term loosely associated with the speed your memory operates at, a system's bus speed dramatically affects virtually every single component in your computer, from your Video Card to, in the case of Socket-7 systems, your Level 2 Cache Memory.
Since we're dealing with Socket-7 motherboards here we'll leave out the specifics from other architectures (specifically the Slot-1 design of Intel's Pentium II), but in general, your L2 Cache operates at your system's bus speed. When Intel announced their 586 line of processors, which due to a flaw in the design and a denied request for exclusive use of the name 586 was eventually renamed to the Pentium Processor, they also announced a new interface for the processors. Migrating from the Socket-3 design of the time which dominated the 486 market, Intel chose to use yet another flimsy Socket interface, dubbed Socket-5. Motherboards using this Socket would also have to boast support for higher Bus Speeds, out of all of the supported Bus Speeds which were originally available upon the release of the first Pentium Processor, the 66MHz bus speed seemed to quickly make itself the standard...a standard which the industry has tried to shake time and time again over the past 18 months.
With the advent of the Intel 430VX Chipset manufacturers began pushing the limits of the 66MHz Bus Speed to new extremes, some of the first VX based motherboards not only took advantage of the 66MHz bus speed which was officially supported by Intel. These motherboards also enabled user's to Overclock their systems (or increase the speed of their computers past the specified limit) by taking advantage of the newly introduced 75MHz bus speed, a bus frequency which was previously only reserved to non-Intel chipsets and the motherboards that housed them. However for the first time, an Intel chipset supported a bus speed, albeit unofficially, that allowed the industry to really have some fun and stay competitive with the rest of the market. VLSI and VIA already had chipsets out or preliminary designs for motherboards which would support this 75MHz bus speed mainly for use with the Cyrix 6x86-PR/200+ (75MHz x 2.0 - officially) so in order to remain competitive it was almost necessary for an Intel chipset to be used on a motherboard that would support this higher frequency.
Soon after these VX boards began popping up with support for the 75MHz bus speed, HX boards seemed to be doing the same...eventually an 83.3MHz bus speed setting was discovered on a few boards here and there, leading to the overclocking revolution you see unfold before your eyes every time you pay just about any hardware site a visit. Throughout all of this however, Intel has still refrained from upping the 66MHz bus speed specification to even 75MHz, they were determined that the 66MHz bus speed wasn't enough of a limiting factor to change it. It was up to the users to seek out the motherboards that supported higher bus speeds to make their newly built systems operate like they "should," and it was up to the manufacturers to produce motherboards that either had hidden undocumented settings or unofficial settings for the 68, 75 and 83MHz bus speeds (the 68MHz bus speed is referred to as the Turbo Frequency of the 66MHz bus speed, used Internally by manufacturers for testing purposes...however it makes a sweet little overclocking tool if you don't want to risk much). The irony of this situation was that most motherboards that supported the 75/83MHz bus speeds and were reliable at those bus speeds were based on Intel Chipsets, not solutions from other companies.