A heatsink is generally needed for every 486 with more than 33 MHz. A fan probably not, as long as there are other fans in the case that moves hot air away from the CPU.

Apart from that, I'm pretty sure the Am5x86 only supports multipliers 3x and 4x, but not 2x as would be required for 66 MHz.

The PSU moves some hot air from the case outside, but I can use a silent slot fan.
I will make a try.
Thank you.

Depends on which 5x86 revision you have. ADW or ADZ? ADZ can work without heatsink.

Thank you, I bought an ADZ version for my purpose.

If it doesn't runs on 66 MHz, there's no issue. I've just want something to test.

Good to know. I didn’t realize that ADZ could handle the higher temperatures.

The Serpent Rider wrote on 2019-12-30, 13:28:

ADZ can work without heatsink.

Yes, it *can*, but it's not meant to run without a heatsink. It should have heatsink+fan installed just like any other model. The ADZ and the later BGC were made for industrial usage and can take up to 105°C, because it should not cause any immediate outage should the fan fail. This isn't the same as offering the choice to just neither install a fan nor a heatsink.

but it's not meant to run without a heatsink

Actually it is. On most ADZ there's no indication, that heatsink and fan is required. But that requirement is labeled on all ADW.

This isn't the same as offering the choice to just neither install a fan nor a heatsink.

On the contrary, industrial grade hardware is designed to work in rather harsh environment 24/7.

If it doesn't runs on 66 MHz, there's no issue. I've just want something to test.

You can't run ADZ on 66Mhz. It can work only with 3x and 4x multiplier, so your options are limited to 75, 100 and 133 Mhz.

The Serpent Rider wrote:

You can't run ADZ on 66Mhz. It can work only with 3x and 4x multiplier, so your options are limited to 75, 100 and 133 Mhz.

Yes 75 MHz is one of my options with 25 MHz bus.

I use to run my i486Dx2 at 80 MHz on my previous Soyo board, so 75 MHz is cool for my 486 VLB project.

It's difficult to add even a heatsink on my cpu, so I can't use an AM486Dx4 enhanced or and i486Dx4...

I want to test the benefits of 16kb L1 cache.

You can look for this CPU: Am486DX2-66V16B
It's the same ADZ stepping, but with 2x/3x multiplier.

Yes I know, but it's very difficult to find this Dx2 66 MHz with 16 kb L1 cache.

JSO wrote on 2020-01-08, 16:25:

It's difficult to add even a heatsink on my cpu, so I can't use an AM486Dx4 enhanced or and i486Dx4...

You could always get a laptop heatpipe type CPU cooler and mount it somehow. I've seen a picture or two of people doing this with 486 boards that have the CPU socket in a dumb place.

And if you still want a fan to cool the fins, just use the stock fan that comes with the laptop cooler and hook it up to a fan speed controller so you can make it silent.

I made 486 heatsinks for my 5x86 chips using cheap 40mm heat sinks & dental wire off ebay. The fan is the most expensive part.

The Serpent Rider wrote on 2020-01-08, 17:37:

You can look for this CPU: Am486DX2-66V16B
It's the same ADZ stepping, but with 2x/3x multiplier.

I'm very lucky!

I found both the DX2-66V16B and Dx4-100V16B with production date both on 2002!!!

I've ordered them! 60.00 $ including shipping I think worthing the price!