Super7 Motherboard Comparison

First of all, with Socket-7 AGP and Super7 systems the most effective way to overclock your processor beyond the specification set forth by the manufacturer is by increasing what has become known as the Front Side Bus frequency or FSB speed.  The Front Side Bus speed is the frequency at which the Level 2 Cache, and Memory Subsystem (under normal conditions) operate at.  The rest of the components in your system, for the most part, derive their speed from that of the FSB.  For example, by multiplying the FSB by the clock multiplier you set on your motherboard you achieve the internal operating speed of your CPU.  By multiplying the FSB by the PCI clock divider set by your motherboard (usually 1/2 or 1/3) you will achieve the speed of the PCI bus.  Therefore by increasing the FSB you will have effectively overclocked your system.  Socket-7 AGP motherboards were never meant to support the 100MHz FSB and therefore only support the 1/2 PCI clock divider, meaning that running the at the 75/83MHz FSB speeds will result in running your PCI bus in excess of 13% out of the specified limit of 33MHz.  This could cause problems with some PCI devices, which is why Super7 motherboards feature a new PCI clock divider of 1/3 which keep the PCI bus frequency as close to 33MHz as possible (100MHz FSB * 1/3 = 33.3MHz). 

With that settled, let's move on to which processors overclock and how far you can push them:

AMD K6 166/200/233

The original K6 series were not the world's best overclockers, on a true Super7 motherboard you should have no problem running any of these chips at the 100MHz FSB with a 2x clock multiplier (200MHz).  Doing so will give you a nice 10% performance boost over a K6 clocked using a  66MHz FSB with a 3x clock multiplier (200MHz) due to the fact that the L2 cache operates at a much higher frequency with the 100MHz FSB.  The 233 can make it up to 250MHz reliably only if you increase the core voltage from 3.2v to approximately 3.4v, and in doing so you must increase the cooling of the processor as well as the system as a whole.  For Socket-7 AGP motherboards the 83MHz FSB (a rare setting on VIA VP3 boards) will probably be your best bet for the maximum performance, however if you happen to have a K6-233 and a Super7 motherboard then by all means try running it at 100 x 2.5...if not you can always stick to 100 x 2.0 which is sill faster than the 233MHz setting with a 66MHz FSB frequency. 

AMD K6 266/300

The next generation K6 chips boasted a lower core voltage setting, resulting in decreased amounts of heat production.  Both the 266MHz and 300MHz K6 parts seem to graciously accept the 100MHz FSB , with 100 x 3.0 as the upper limit on both of the chips (some 300's will make it up to 100 x 3.5 using a 2.3 - 2.4v core voltage setting).  Using the 66MHz FSB on a standard Socket-7 AGP motherboard you can easily push the 266 up to 300 and the 300 up to 333 without too many problems, although you're better off using a higher FSB frequency if you are looking to gain the most performance increase out of your overclocking. 

AMD K6-2 266/300/333

AMD's K6-2 is the topic of many discussions on-line these days, as any chip with this much potential should be.  One of the topics brought up has been the fact that the 266MHz K6-2 is rated for use with the 66MHz FSB, while the 300MHz part was intended for use with the 100MHz FSB.  The K6-2 266 doesn't seem to have any problems running at 100 x 3.0 making it virtually identical to the more expensive K6-2 300 except for the fact that the 300MHz unit has more of a chance of working at 350MHz.  If you only plan on running your system at 300MHz, and don't mind doing a bit of overclocking, save yourself some money and pick up the 266MHz K6-2, pop it in a Super7 board and enjoy some amazing performance at 300MHz.  The K6-2 can be used in older Socket-7 AGP motherboards as long as they support the required 2.2v core voltage (in some cases 2.1v has been known to work), however you won't be receiving the full performance benefits of your chip since you won't be running it at the 100MHz FSB.   The 300MHz chip will make it up to 315MHz (90MHz x 3.5) however 100 x 3.0 is still a faster setting, once again, due to the increased FSB frequency. 

The next chip in the K6-2 processor family will be the unique 333MHz part.  What makes the 333MHz part unique is that it is rated for use not with the 66MHz FSB, not even the 100MHz FSB, rather the 95MHz FSB using a 3.5x clock multiplier.  Since the 95MHz setting is not standard it requires a specially modified motherboard to run within specification on, however most users will be pleased with running their 333MHz chips at 350MHz using the 100MHz FSB.  You'll definitely hear more about this chip shortly when AnandTech takes an even closer look at the AMD K6-2.

Cyrix 6x86MX

The 6x86MX seems to be a no-go at the 100MHz FSB, if you plan on using the Cyrix processor on a motherboard you're better off sticking to a decent Socket-7 AGP motherboard or shelling out the extra cash for a K6-2 and pairing that up with a Super7 motherboard.  The new M-II from Cyrix may prove otherwise, but for now, the 6x86MX doesn't seem to hold that much of an advantage if any over the competition in the Socket-7 AGP world and definitely falls in last place in the Super7 market.

Intel Pentium MMX

Don't think AMD users get to have all of the fun with Socket-7 AGP and Super7 motherboards.  The Pentium MMX is a great processor, especially for use with the 100MHz FSB.  If you're looking for ways to squeeze more performance out of your aging Pentium MMX processor, toss it in a Super7 motherboard and enjoy the same 10% increase in performance with the 100MHz FSB once thought to be only reserved for Super7 processor owners.  The Pentium MMX 233 is known for being a wonderful overclocker, and by upping the voltage from 2.8v to a dangerously high 3.4 - 3.5v you shouldn't have a problem getting some experience with the Pentium MMX at 300MHz using the 100MHz FSB although running at that setting for extended periods of time isn't recommended.  The sweet spot for the Pentium MMX 200/233, due to Intel's incredibly high yields is 250MHz (100 x 2.5) and you will be more than pleased with the performance this processor can give you.

What does the future hold for the Socket-7 market?   The first signs of new overclocking possibilities have appeared, and they have arrived in the form of the 112MHz FSB.  A setting present on most BX motherboards is now appearing on Super7 motherboards, while the first generation of 112MHz capable Super7 boards are still a bit flaky expect to see much more of this setting in the future...after that, who knows what could be next to pop up, 125MHz...133MHz?  ...and beyond?   Looks like there could be more left in the Socket-7 market than we originally thought.