1. No, i know no CPU with 1.5 Multipler on Socket 3. (Maybe Pentium Overdrive ???)

2. get a Industrial 3.3V DX2 66 16BGC and it will overclock up to 4x33 and more 😀

It depends on the 486DX2 CPU.. some may work, some will run unstable.. but best Overclockers are 3.3V Parts.

I have the same motherboard and it supports a FSB of up to 50 MHz (mine currently has the 486DX-50 installed).

A 486DX2-66 has a built-in multiplier of 2 running on a FSB of 33 MHz. What you can try is to just set the FSB at 40 MHZ and see if the motherboard will post.

You might have to apply some wait states in your CMOS setup (particularly if you have VLB cards installed) and remember to set your AT Bus clock divider to 5 (40/5 = 8 MHz).

I never had any Luck overclocking DX2-66’s

SX2’s yes
SX-25 -> 40mhz yes
DX2-50 -> 66mhz Yes

I actually had trouble getting a real dx2/80 operating at proper speed stable but the dx4’s/120 ran fine on the same board Go figure

rmay635703 wrote on 2020-06-26, 20:15:

I never had any Luck overclocking DX2-66’s […]
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I never had any Luck overclocking DX2-66’s

SX2’s yes
SX-25 -> 40mhz yes
DX2-50 -> 66mhz Yes

I actually had trouble getting a real dx2/80 operating at proper speed stable but the dx4’s/120 ran fine on the same board Go figure

The DX2-66 I had back in the day ran fine at 80Mhz for the most part. There were a few things it din't like, so I modified the case to add a FSB jumper to the front of the case that allowed me to switch between 33Mhz and 40Mhz fsb.

Guessing the problem was simply overheating at 80Mhz and pretty sure all I had was a super lame heatsink with maybe a fan and I probably didn't even use any thermal paste.

No 486 CPUs use a 1.5X multiplier. POD used 2.5X (with a fallback to 1X). So far nobody has found any way to set multipliers in between. i486DX4 was supposed to support 2.5X too, but that option never made it to production versions despite showing up in the datasheets. 1.5X could be possible on some of the single clocked 486s if you were willing to design an interposer with a PLL. It's a lot of effort for a fairly useless feature in my opinion.

That colleagues. Heatsink + fan is in place so I will give it a try. More later. Thank you

I got a overdrive dx266 running at 80mhz 2x40fsb

Ran ok but got really really hot after 15 mins of intensive gaming but those overdrive come with a tiny heatsink no fan

Update: i486dx/2 66 Running Fine at 2x40 with large heatsink only. Good success! Thanks again all

There was a 486 DX3 planned by intel which was supposed to run at 83Mhz (33x2.5) but it never made it out of intel's lab as it was not faster enough compared to the DX2-66 and it was also probably not slow enough compared to the DX4-100