View Full Version : 486 Dual CPU Motherboards?

February 25th, 2004, 01:29 PM
I'm just curious if any of you'se out there know of any mobos made to handle two 486 processors?

While I know for a fact dual-CPU mobos never became widely known until the Pentium dynasty came about, apparently dual-486 boards do exist, but are quite rare as it seems (through my limited research so far) because they only came out with the DX4's (100/120MHz) the same time the early Pentiums were coming out, which spelled the end of the 486's.

I ask because of an interest in doing some old-fashioned computer-hot-rodding. My personal project at college (Computer Sciences and Technologies course) is to overclock a 486 as much as possible with the aid of liquid cooling. I even pondered if I had a dual-486 mobo, overclocked (two 486-DX4 120MHz' overclocked to 150MHz each = 300MHz 486 system!) if it could run Windows XP Pro. lol

Any input would be greatly appreciated. Even getting one 486 120MHz to run stable at 150MHz would be quite a feat, and to be water cooled, at that. Two would be godly, hehe.

February 27th, 2004, 12:19 PM
First off the 486/133 by AMD can be clocked to 40x4=160 with the normal heatsink and fan with no problems (ran one for years this way and it still works, can get you the chip information if needed since there were 2 types of 133).

I have never seen or heard of a dual processor 486 motherboard (dual pentium boards were made but are rare).

I have seen quite a few boards with a 486/sx chip on them and a socket for a DX upgrade chip (this would disable the other chip and take over the motherboard). I have also seen a 386 board that would take an early 486 processor upgrade in a seperate socket.

Even if you find such a beast windows NT (which uses intels method of dual processors started with the pentium line) will not use both processors. not sure of any other OS.

February 29th, 2004, 09:17 AM
There were dual processor 486 systems. I don't remember there being motherboards for the home market though - you probably had to buy a system to get the motherboard. And it would have been an expensive system.

The 486 is not designed to work in a multi-processor configuration. It can be done, but it takes extra chip-set support. The Pentium line corrected this flaw by adding cache management primitives that have multi-processors in mind.

As UnknownK pointed out, you have an operating system issue too - it was a non-standard configuration for a 486, so Linux might not even support it. (Probably doesn't support it is more likely ...)

An interesting way to soup up a 486 was to use SRAM as main memory. Jerry Pournelle had a 486 he named 'Cheetah' that had 2MB of SRAM as memory. SRAM is bigger than DRAM and runs hotter, but it was zero-wait state memory. It's the equivalent of running entirely out of the cache, which is quite fast.