Depends on the size of the heatsink and any case fans I would say.
My P200 has a aluminum heatsink only but its kind of large (1.75x1.75x1.75 🤣), but it sits just a few inches from the 80mm front case fan blowing on it. CPU stays cool enough clocked up to 290. Good design, less noise.

My 486 PC never came with any case fans installed and the CPU heatsink is quite tall compared to other 486 coolers i've seen (approx 45mm).

You really don't need much cooling for those things, a decently sized passive heatsink (i.e, average Pentium heatsink, minus the fan) with a little bit of case airflow should do fine. IIRC, even the higher-clocked 486 chips never drew more than 5-6W.

Wow a 45mm heatsink on a 486? That's quite nice! I thought I had some pretty nice 486 heatsinks, but they're no more than 18mm tall.

The DX/4-100 is quite happy with passive cooling. That's what intel provides on the overdrive version of the chip.

Just touch it. If you run it for a few minutes and can't keep your fingers on it, then it's too hot! 😁

Thinking about it, the Voodoo 3 I ran had a passive heatsink and clocked at 166. Puppy was too hot too hang on to but ran fine that hot.

bushwack wrote:

Just touch it. If you run it for a few minutes and can't keep your fingers on it, then it's too hot! 😁

Thinking about it, the Voodoo 3 I ran had a passive heatsink and clocked at 166. Puppy was too hot too hang on to but ran fine that hot.

The tall heatsink on the CPU is warm to the touch... not very hot at all so i'm guessing it's safe 😀

While i'm on the subject of passive cooling, do you think one of these would be good for passively cooling my Matrox G400 Max? It's a Zalman ZM NB47J chipset cooler (looks quite similar to my 486 heatsink).

My Ga400 Max has got a small/thin heatsink and fan on it at the moment which sounds quite whiny.... I know the standard G400 comes with a passive cooler but i have no idea how much hotter the G400 Max is?? Do they even run that hot?

Ha, I was looking at that exact heatsink last night. As it turns out, it's the perfect size for a 386.

Anonymous Coward wrote:

Ha, I was looking at that exact heatsink last night. As it turns out, it's the perfect size for a 386.

It's quite similar to the tall thing i have cooling my 486 (except mine is copper and does not have mounting holes). I'm trying to decide if this Zalman heatsink will be any good with a G400 Max? (i hate those whiny little fans!).

I'm pretty sure the 486DX4-120 I had used both a heatsink and fan, but I think the fan died at one point and we used a desk fan blowing into the case to keep it cool enough to run (mostly) stable until we could get a replacement.

Intel dx/4 is 0.6 micron
amd dx/4 is 0.5 micron or sometimes 0.35 micron
cyrix dx/4 is 0.65 micron

I would say running at stock frequency, none of these chips should require a fan if the headsink is at least 15mm tall. Overclocking may require use of a fan, especially on the intel and cyrix parts. am486 and 5x86 on the 0.35u process are usually fine when overclocked just using a passive heatsink.

Even an Intel DX4 at 120 MHz doesn't need a fan, provided the heatsink is big enough.

I dug up an old photo of my 486 box (sorry about the miserable quality):

The heatsink is epoxied to the CPU (speeds up CPU swaps).

Yeah when I occasionally run the 'ol Am5x86 @ 160, I only have a passive heatsink setup for it. Those are 0.35µ though so they barely get warm. All of those old CPUs only put out a few watts of heat. Consider that the 5-volt 0.80µ DX/2 50 chips were heatsink-optional. 😀

Wow the boards look really warped in that pic.

My 486DX4-120 (AMD) must have had too small of a heatsink because it would get really unstable without the fan, especially during the summer when the room temperature approached 95-100 degrees F (35-38 degrees C).

I never tried overclocking it because it's real limiting factor at the time was not being able to do floating point math as fast as a pentium 😀

I went and got this Zalman chipset cooler to replace the small and noisy cooler on my Matrox G400 Max...... I just hope it does the job!

I removed the fan from the old "flat" heatsink and then ran Morrowind for half an hour to see how much the G400 Max heats up.... It got fairly hot but i could still hold my finger on the heatsink without burning. The original heatsink is very small and flat with a whiny 40mm fan... I'm hoping this Zalman cooler is adequate at passively cooling my G400 Max 😕 (the Zalman heatsink is 47mm tall and will block the PCI slot next to the G400!)

I bought one of those to replace a mobo chipset active cooler. It is rather tall and will be more than adequate for a G400.

486DX4 is a 3.3v CPU and in theory doesn't require any form of cooling,even a 100mhz version...But,it is a good practice to add a passive headsink,any kind/size will be enought. I've got Like 20 of them,and only one is hot in touch...