Socket 7 / Super Socket 7 Motherboards and pushing their limits

If your into retro computers probably one of the more common boards you’ve come across uses the socket 7 or super socket 7 for the CPU. socket 7 spanned almost the entire 1990’s and you can use a socket 7 motherboard to build everything from a capable DOS platform to a PC that can run windows XP. The CPU’s that can be used in a socket 7 board range from the 75mhz Pentium to the 550mhz K6-2 and K6-3. Intel abandoned the socket 7 after the 233mhz MMX Pentium 1 but other companies like Cryix and to a greater extent AMD pushed socket 7 into the super socket 7 which is a backwards compatible extension of socket 7 for their k6 CPU’s. This extension created a cheap upgrade path for many people and extended the life of this CPU socket. That long life means that a retro gamer enthusiast can use a cheap and common socket 7 motherboard to make a very capable and well rounded 166mhz Intel based DOS PC or a capable k6-2 or 3 Windows 98 machine or with adequate RAM a k6 powered windows 2k or XP machine for “light” gaming and computing. I used a k6-2 500mhz machine for Windows 98 and then windows XP for a large part of my college life. I also use a socket 7 board with a 200mhz MMX Intel chip for my official “fast DOS” machine for classic gaming.

Here is a typical later model super socket 7 board. It has a variety of PC extension slots from ISA to AGP and PCI allowing you to use a huge variety of video and sound cards for DOS or Windows. You could slap a 166mhz Pentium a Virge video card and a Sound blaster 16 on here and have a computer that would play most DOS games fine or a 450mhz K6-3 a voodoo 3 and a sound blaster live! and have a great Windows 98 machine. These motherboards came in both ATX and older AT designs which featured AT keyboard ports as well as AT power connectors.

The socket itself is very simple. Just raise the handle and the socket is ready for a CPU to be inserted.

Lower the handle after the CPU is inserted slap on some thermal paste as you see in the image and then slap on a heatsink/fan and your good to go.

Despite the relatively high speeds of later socket 7 CPU’s they are still running on what was at the time older and limited boards. a 450mhz k6-3 is really only maybe equal to a 266 or 300mhz or so Pentium II CPU in a Slot 1 motherboard. The Intel Pentium II and especially Pentium III had much better floating point math abilities and using a socket 7 board in the late 90’s was really seen as more of a budget friendly course for PC upgrading rather then a power platform for gaming.

Slot 1 is the format that Intel moved onto with its Pentium II and early Pentium III CPU’s. The later Pentium III’s went back to a socket format that resembled socket 7 but its not compatible.

PUSHING THE LIMITS

I’ve used plenty of socket 7 boards for DOS. my main “fast DOS” PC used a 200mhz MMX CPU and my all purpose DOS PC uses a 133mhz CPU but I wanted to see how far the Super Socket 7 design could be pushed. I only used what spare parts I had around with the exception of the CPU that I acquired online.

The case I used is a pretty standard ATX case. I have a DVD as well as CD-ROM drive installed. I have two Hard drives installed. One is a 6GB drive where I have Windows 98SE installed and a secondary 40GB drive for files and games. I also have a 1.44MB floppy drive installed.

For video and sound I wanted to stay strictly period correct. For sound I originally went with a PCI Monster Sound MX300 from 1998 but it tended to give me some stability and reliability issues with this motherboard (common on VIA chipsets I’m told) so I dumped it for a simple ISA sound blaster 16. A outdated and mediocre card for something of the late 90’s era but supported by just about everything and able to give great DOS compatibility since its ISA. For sound you could also go with a AWE64 or a later Sound Blaster Live!. For video I used originally installed a Nvidia TNT2 Ultra AGP card. The TNT2 Ultra is a high end card for 1999. Its fairly backward compatible so you get good DOS compatibility and its also a very good card for OpenGL and D3D games. other choices would be The Diamond Stealth III S540 which is supposedly slightly more DOS compatible but a rather mediocre Windows 98 performer.

Perhaps the best choice for a pre 2000 socket 7 would be a Voodoo 3 seen directly above. The Voodoo 3 performs better with Glide games and can be a faster card in certain games as well as giving a very nice picture but it has half the video RAM of the TNT2 ultra and is limited to 16 bit color where the TNT2 can do 32 bit color. The Voodoo 3 supposedly “scales better” with an AMD K6 since it specifically supports the AMD 3DNOW! The version I’m using is the standard AGP version with VGA and S-video out. There is a PCI version as well as a high end faster AGP version the v3 3500 but it uses a proprietary DVI connector that requires a breakout box dongle.

The motherboard I’m using is one I had on hand and is a EPOX EP-MVP3G2 which is a good performing Super Socket 7 board that offers easy overclocking with jumpers in the lower right corner of the board. I’m running 512MB of SDRAM. This particular motherboard supports everything from the Pentium 166MMX to the AMD K6-III.

The most important part of stretching socket 7 to the limit is the CPU. The fastest available socket 7 CPU would be the AMD K6-III+. These CPU’s go for about $15 to $20 but be sure you get a + chip since a standard K6-III does not overclock well. You will notice the AMD K6-2 comes in higher clock rates, up to 550mhz and although its very doable to run something like XP on a 500mhz K6-2 the K6-III is the newer chip and the better overall performer. Originally the K6-III only was sold up to 450mhz and was a very poor overclocker but fortunately AMD made the almost identical K6-III+ for the mobile pc market. Thankfully the K6-III+ uses the same socket 7 form but requires less voltage making it an excellent overclock candidate chip that also offers rock solid stability at higher then rated speeds. Some motherboards may need a BIOS update to accept the K6-III+, mine did not.

If your going to overclock try to make sure you have adequate cooling for your CPU. I replaced the standard heatsink and fan with a larger heatsink designed for a later K7 chip.

using the standard settings for the K6-III of a 100 fsb and a multiplier of 4.5 we get the rated 450mhz.

Now simply changing the fsb to 112 and the multiplier to 5 we get a CPU speed of 560mhz which if were being generous puts this CPU on par with a Pentium II-350 for some games or applications. The system is also extremely stable at this speed with no issues or crashes running Windows 98 for long periods. Games like Half-Life ran beautifully on this setup and I would think this particular machine would meet almost all of your late 90’s gaming needs. I did attempt to bump the multiplier up to 5.5 giving the CPU a speed of 616mhz but apparently this did not jive with something and Windows crashed after boot on all occasions I tried this. I have read that several people have gotten the k6-III+ to run stable at 600 and 616mhz so I’m pretty sure it is possible with some tweaking and possibly a different Super Socket 7 board.

 

All and all it was a fairly cheap and fun project and goes to show how far the old and reliable socket 7 could be pushed. The K6-III+ is a great chip and overclocks super easily and stays very stable. Just remember not to set your expectations to high, the K6-III+ was sold as a budget CPU rather then a performance CPU so even though it’s a nice performance kick in the butt to the then outdated socket 7 it will still start to struggle in many post 2000 games and at higher resolutions.

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