You can use strips of Thermal Tape. Ones made by 3M are generally of good quality.

Double-sided thermal adhesive tape will work. I've used it on my Cyrix DX2-50 when the old tape wore out. It's the best semi-permanent solution compared to using thermal epoxy, and won't ruin the printing on the chip.

Does your 486 motherboard have any of those socket tabs on the sides of the CPU socket?
The dimensions of the socket 3 ZIF sockets have the same dimensions as s7, s370 all the way to sA and this would probably be the easiest fix for you, if applicable 😀

edit: Looks a bit like the metal frame on this black heatsink, as s3 usually only had 2 of those tabs (I still forget what they are really called, my apologies 😊 ) and these are usually not located directly on opposite sides. But with such a metal wire thingy most usual s7 heatsinks will fit.

Many s3 boards didn't have any of those tabs though and in that case you'll need to fix the heatsink directly to the CPU itself somehow.

I just used a good amount of thermal paste, they're pretty light and it seems to work fine.

If it's a DX-33 you don't actually /need/ one, I had a DX-33 from the early 90s that never had a heatsink, shipped without, and used it that way.

Heatsinks are not required for the AM486-DX2-50, and are not needed on any chips except for those faster than the DX2-66. And almost all 486 coolers do NOT use motherboard heatsink attachment, instead they use clips that attach directly to the ceramic of the CPU. Here is the one I use: https://www.amazon.com/IEC-486-CPU-Cooling-Fan/dp/B003U48PSC

Don't waste your money, you don't need one, those chips can go up to around 90c with no issue, and really only have issues if they go above that temp. Too hot to touch is around 60-70c which is a perfectly acceptable load temp for most CPUs

If you really want to use the heatsink, go right ahead, it's your money. Make sure to apply thermal compound to the center of the chip, and when attaching the heatsink, don't flex the clips on there, instead take the fan off, remove the clips, attach the CPU, replace the clips and fan, and it will all hold together.

I can attest to it not needing a heatsink, I have an Intel 80486 DX2-66 I've been running non-stop for about 4 years now without a heatsink, it runs 24/7, mostly in WFWG311 with AfterDark so it's always number-crunching on something. I only just recently found out Vetco (electronic place near me) had a huge cache of Cyrix passive heatsinks from Cyrix DX2-66 chips with self-adhesive backs on them for a buck fourty-nine each ($1.49).

The AM486-DX2-50 might not need a heatsink but the cpu is a 80486DX-50, so the external bus will also be clocked at 50MHz (assuming the AM486-DX2-50 is 50/25MHz). The DX-33 definitely runs without heatsink.

I tried to find an official intel datasheet (no success at ark) for the cpu, but I only found one that specifies a max Tcase, so it's up to the user to figure out whether or not to use a heatsink.

Since creepingnet says that his 486DX/2-66 runs fine w/o heatsink I'll just use my DX-50 without any heatsink and make sure that case has a fan (which it hasn't atm, but holes for a 80mm fan at the front).

@Tetrium: the board does not offer much space around the socket: It's a Soyo with 4xPCI/4xISA/1xVLB

Will the TAG RAM be fast enough for 50MHz? The TAG RAM is 12 ns and 15ns (256k):

cpu:

I still need to verify that the system runs stable and the RAM is ok, any recommended tool for this task?
x86memtest didn't start at all (does it still support '486s?)

eax wrote:

I still need to verify that the system runs stable and the RAM is ok, any recommended tool for this task?
x86memtest didn't start at all (does it still support '486s?)

Just to be sure, did you try to run memtest from a floppy and not from an optical disk? Afaicr booting from CDROM drive wasn't supported till a bit later in PC evolution.

Tetrium wrote:

edit: Looks a bit like the metal frame on this black heatsink, as s3 usually only had 2 of those tabs (I still forget what they are really called, my apologies 😊 ) and these are usually not located directly on opposite sides. But with such a metal wire thingy most usual s7 heatsinks will fit.

Metalcpuclip.png

I believe those are called bale clips, or "z" clips.

eax wrote:

The AM486-DX2-50 might not need a heatsink but the cpu is a 80486DX-50, so the external bus will also be clocked at 50MHz (assum […]
Show full quote

The AM486-DX2-50 might not need a heatsink but the cpu is a 80486DX-50, so the external bus will also be clocked at 50MHz (assuming the AM486-DX2-50 is 50/25MHz). The DX-33 definitely runs without heatsink.

I tried to find an official intel datasheet (no success at ark) for the cpu, but I only found one that specifies a max Tcase, so it's up to the user to figure out whether or not to use a heatsink.

Since creepingnet says that his 486DX/2-66 runs fine w/o heatsink I'll just use my DX-50 without any heatsink and make sure that case has a fan (which it hasn't atm, but holes for a 80mm fan at the front).

@Tetrium: the board does not offer much space around the socket: It's a Soyo with 4xPCI/4xISA/1xVLB

Will the TAG RAM be fast enough for 50MHz? The TAG RAM is 12 ns and 15ns (256k):

tag.jpg

cpu:

cpu.jpg

I still need to verify that the system runs stable and the RAM is ok, any recommended tool for this task?
x86memtest didn't start at all (does it still support '486s?)

Well, not to mention it will label on the CPU if a heatsink and/or fan is required (Look at pictures of DX4-100s)

And Phil's (From Phil'sComputerLab) benchmark pack has some memory testing utilities in it.

Tetrium wrote:

eax wrote:

I still need to verify that the system runs stable and the RAM is ok, any recommended tool for this task?
x86memtest didn't start at all (does it still support '486s?)

Just to be sure, did you try to run memtest from a floppy and not from an optical disk? Afaicr booting from CDROM drive wasn't supported till a bit later in PC evolution.

I used a 3com905 PCI network card and PXE to boot the box.
The debian etch install boots fine via PXE on the i486 and the x86memtest does too on a different (686) machine, I suspect x86memtest expects something > i486. I'll try out some older versions.

Tetrium wrote:

Just to be sure, did you try to run memtest from a floppy and not from an optical disk? Afaicr booting from CDROM drive wasn't supported till a bit later in PC evolution.

This. To get Memtest to run on my Win95 Pentium (1) build, I had to create a memtest bootable floppy disk. I could not get the CDs I had to boot at all. Worked fine. Just check their website and peruse the "older editions" section to find it.