I doubt that anyone has done this at least not in recent memory so it is worth a shot and I already know that overclocking dx2-66 to 80mhz works like a charm when the board is up to the job. If this trick works I wouldn't be surprised that it becomes a popular option for those wanting to avoid the expense of buying a proper dx4.

My Intel dx2-66 won't do 80mhz, but AMD 5x86-133 does 160 no problems, so it's not the motherboard.
There are no voltages selectable over 5v, which is likely why it doesn't work, but I do get a post screen at 80mhz.

Imperious wrote:

My Intel dx2-66 won't do 80mhz, but AMD 5x86-133 does 160 no problems, so it's not the motherboard.
There are no voltages selectable over 5v, which is likely why it doesn't work, but I do get a post screen at 80mhz.

this is reasonable because all of intel's dx2 are old 5v parts, only amd and cyrix made 3.3v dx2 models.

Is it not the case that the multiplier jumper switches between 2x and 3x for DX4 parts, but only 1x and 2x for DX2? In any case the 50% overclock seems pretty extreme.

firage wrote:

Is it not the case that the multiplier jumper switches between 2x and 3x for DX4 parts, but only 1x and 2x for DX2? In any case the 50% overclock seems pretty extreme.

guess not. amd's 3.3v dx2 came out in 1995 which was pretty late(1992 for intel dx2) and about same time as their dx4, so its quite likely that they would produce their dx2 and dx4 parts on the same line.
i looked at some mainboard manuals and some do mention that for amd dx2/dx4 wt models, the jumper for cache mode sets 2x and 3x. i wish someone with these cpus would give it a try.

I had one motherboard/cpu combo, that when I set cache mode (via jumper) from WT to WB it actually changed the multi from 2x to 3x. It was some AMD DX2-66 3V. It worked fine at 100MHz - not sure if I tried 3x40MHz. But the thread should be somewhere around here...

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Edit... Found my thread:
AMI Super Voyager PCI II S724 - 486 motherboard