Socket 7 and the Onset of the 100MHz Bus: A New Lease on Life

The Socket 7 form factor for processors has been, in the last few years, a boon to all the people looking for powerful processing at a reasonable price (the "Bang for your buck" market). By waiting for the alternative CPU folks (i.e. Cyrix, AMD and IDT) to crank out a lower cost solution to the many Intel products, we were all able to save some dollars to spend on other things, like software, bigger hard drives and multimedia peripherals. This platform has provided many hours of happy computing for tons of people. Luckily this situation will only get better with upcoming improvements to the venerable Socket 7 motherboard.

Any time now, we’ve been promised the next step in the x86 computing revolution….the onset of the 100MHz bus speed. Our older motherboards that run bus speeds of typically 60, 66, 75 or even 83 will be increased to the Holy Grail mark of 100MHz clock speed. This holds the promise of providing significantly better performance. Intel is racing the Alternative CPU manufacturers toward a showdown of 100MHz bus speed products. The payoff appears to entail a lot of money and could determine market share for years to come. Success in this area could give us great performing alternatives at less than premium prices (a good thing). Failure could lessen our choices and squeeze some players out of the processor business, lessening competitive pricing and freedom of choice (a bad thing).

What is Bus Speed?

To those wondering what all this 100MHz bus speed talk is…..here it is in a nutshell. The clock speed of the components generally between the processor and the PCI slots will speed up significantly. That’s approx. 50% when going from the typical 66MHz bus speed to 100MHz. This speed up includes your most important components like the motherboard chipset, the level 2 cache and the main memory. It’s debatable that these changes will effect your PCI devices, which typically run at ½ your bus speed. Most PCI devices run fine at 33MHz, but begin to get real flaky when pushed beyond. This issue may be avoided by running PCI cards at 1/3 the bus speed to maintain their 33MHz sweet spot. Accelerated Graphics Port (AGP) video cards will also benefit from this increase.

If you haven’t figured it out yet, your processor speed is simply a multiple of your bus speed. For example, a K6-200 currently runs a 66MHz bus speed that uses a multiplier jumper setting of 3X to multiply the bus speed up to 200MHz for use by the processor. This equates to a 66MHz x 3 = 200MHz setting. So the upcoming K6-300 processors that promises to utilize the 100Mhz speed will also utilize a 3X multiplier (3x100Mhz=300MHz). Why does this all manner to alternative CPU owners?

Keeping Socket 7 Competitive

If the Alternative Crowd is to keep competitive with Intel performance in the next year, the 100Mhz bus speed is a necessity. AMD seems poised to provide the leadership in this area. The success or failure of motherboard designs that can run at 100MHz reliably is key to making AMD a continued success in the processor business. Intel will present some very stiff competition this year with their new, Deschutes .025 micron Pentium II chip and their upcoming BX chipset. If AMD is to remain competitive, they’ll need to give the Socket 7 market a kick in the pants.

Intel would love to kill off the Socket 7 architecture, once and for all by releasing their version of the 100MHz bus speed product first. This could create a perception of the Slot 1 architecture being technically superior and put doubts in the minds of the average users (like you and me) about the continued viability of the Socket 7 platform. Innovation and performance at a cost effective price point is what will keep the Socket 7 competitive.

Performance Gains

The performance of some early released prototype 100MHz boards seem to be running from 10 to 15% over the average 66MHz bus board (keeping the processor speed the same). Add to that cooler parts that’ll go beyond the 300Mhz speed mark and AMD’s future looks bright. The Slot 1 version of the 100Mhz system boards don’t seem to promise improvements this significant due to differences in how the level 2 cache is handled. In the Slot 1 design the level 2 cache is running at half the processor speed already. For instance a typical Pentium II 300Mhz system runs it’s L2 cache as (300/2 = 150MHz). This is already much faster than the typical 66MHz L2 cache speed of the typical Socket 7 motherboard. Increasing it to 100Mhz is an exciting performance boast to the L2 cache on the Socket 7 platform, but will not be a factor on Slot 1 designs.

Whose Gonna Be a Player?

Some interesting fallout may occur with this attempt to get the Socket 7 market to the 100MHz bus speed. What happens if AMD succeeds first with their upcoming.25 micron part? If they can keep costs down with good yields and get reliable motherboards to support the processors, the alternative market will rapidly move to this emerging standard.

Can or will Cyrix follow AMD into this arena? Will Cyrix just continue selling their current MMX line and move development to the Slot 1 architecture based on recent agreements with Intel? Can IDT keep pace and make the move?

AMD may be left alone defending the next generation Socket 7 boards. A number of people complained about the move by Intel to a new proprietary slot every year or two. Now AMD may also be alone in supporting this revved up version of Socket 7. Going head to head with Intel without having their backs covered by Cyrix and IDT might make for an unfair fight.

What’s the difference between existing 75MHz and future 100MHz systems

For those already overclocking their 66Mhz bus to 75MHz ( or perhaps even 83Mhz) or just running a supported Cyrix processor at a 75MHz bus speed, the upcoming 100MHz speed will be an incremetal increase but won’t revolutionize their computing. The excitement of the 100Mhz is the promise of an officially tested and industry approved solution. This means that we will no longer have to push our current components to the edge of their stability in order to satisfy our need for speed. Vendors will hopefully crank out sufficient memory and processors to provide the reliably fast solution we used to get with a roll of the dice.

Now, if someone wants to get a new motherboard/processor combo that works at an overclocked rate, they’d have to research some components and then hopefully get lucky. No one can guarantee the ability to overclock, but if it can happen that’s great. The difference between currently overclocked systems and the upcoming 100Mhz bus speed is that we will hopefully have a standard that will allow us to achieve the equivalent of super overclocking with components fully tested and certified to work at those speeds. No more hoping we’ll get lucky when we buy a K6 and hope we got a good one with some margin adequate for overclocking. No more spending hours tweeking the BIOS memory timing to find the most stable setting, only to have Windows crash again.

How Will an Upgrade Go

Anytime a technology has been pushed to a new level, like this bus speed increase, they’ll be problems. Neither Intel nor AMD has yet to officially release any combination that supports 100MHz to the general public as a fully tested and supported speed. Some users have found very flaky undocumented 100MHz bus speed settings that are better left alone, unless reformatting hard drives is a past time that excites you. This is not suprising because there is a lot of details to iron out. Like what kind of memory can be guaranteed to work reliably and who’s making enough of it?

Essentially everyone using 72 pin EDO or Fast Page Mode DRAM SIMMs will need new memory. SDRAM (168 pin DIMM) will initially be the ticket, but even existing SDRAM sticks may be taxed when run at 100MHz. There is a growing concern that a lot of the 10nS SDRAM modules already in systems may prove inadequate when running this faster bus. Enough compatibility problems with SDRAM modules in current systems seems to point to more problems initially. For totally reliable operation, it’ll be necessary to buy from reputable dealers qualifying parts under the so-called "PC100" label.

The PCI components already in your current system should be adequate if motherboard designers stick to the current 33Mhz standard speed for the PCI bus. In the future this will most likely be increased, but not in the initial wave of 100Mhz bus speed motherboards.

Conclusion

The 100MHz bus speed is a good thing for the future of Socket 7 designs and the health of alternative CPUs everywhere. For every significant speed increase seen in computer designs, the cooler the applications look that run on them. We’re coming to a time when gamers, multimedia addicts and even business people won’t feel left behind if they purchase systems based on innovative Socket 7 designs. Typically if you buy an alternative CPU it’s seen as a sort of compromise. Those days could be numbered if the promise of this upcoming 100MHz bus speed designs become reality. Intel can’t rest easy yet, Socket 7 still has some life left.