Jo22 wrote:

The Am386DX-40 gets barely warm (as opposed to a 486DLC). AFAIK, it differs from the intel ones by using a static CMOS design.

AMD used an 800 nm process.
Intel started with 1500 nm in 1985, and later moved to 1000 nm.
The 1000 nm should be quite close to 800 nm, especially at the end of its lifetime, when the process was fully matured (the first 486es were also made on 1000 nm, even the DX-50 and DX2-66).
Which is why I think the later 386DX-33 CPUs could probably overclock quite well, and should be able to run at 40 MHz as well.

I'd say use AS5 with a good copper heatsink fan combo to keep it cool maybe see if one of the AMD Thunderbird coolers can be mounted, then it would run near ambient 😁

einr wrote:

A DX2/66 though is the very last processor I would run without a heatsink. As soon as you're into DX2/80 or DX4/100 territory it's heatsink at least and probably a small fan, too.

dx2-66 is actually the hottest 486 from intel, generating more than 6 watts, while dx4-100 generates about 4watts.

as for dx2-80, 5v models exist from amd and cyrix, generating 8 watts as the hottest 486 in the world. but they are pretty rare and 3.3v ones are more common, which generates around 3watts.

noshutdown wrote:

as for dx2-80, 5v models exist from amd and cyrix, generating 8 watts as the hottest 486 in the world.

Intel DX2-66 can run without fan. If you put a fan on it, you can easily overclock it to 80 MHz, essentially giving you the same as an AMD or Cyrix.
I've run mine like that since 1996 or so 😀

I have a heat sink and fan on there, but without thermal paste. I might put some on, I have some Arctic silver 5 somewhere. Although, I am still having a really weird issue, which apparently is not related to the heat of the CPU. I have this 486 built in to an ATX tower. It was hard to get it to fit but with a bit of tinkering I got the card and motherboard seated. But when the tower is on it's side, so that the MB is horizontal my serial mouse will work. when I put the tower vertical it does not. All of the cards are in there firmly without any wobble. I can only think that the board and/or cards are slightly twisted in some way as a result of having to get them to fit in to a non-AT board and and when it is vertical it is enough pressure to stop the serial port working. It is the weirdest problem I have ever seen and it is driving me crazy! I wish I had a proper AT case.

rick12373 wrote:

I have a heat sink and fan on there, but without thermal paste. I might put some on, I have some Arctic silver 5 somewhere. Although, I am still having a really weird issue, which apparently is not related to the heat of the CPU. I have this 486 built in to an ATX tower. It was hard to get it to fit but with a bit of tinkering I got the card and motherboard seated. But when the tower is on it's side, so that the MB is horizontal my serial mouse will work. when I put the tower vertical it does not. All of the cards are in there firmly without any wobble. I can only think that the board and/or cards are slightly twisted in some way as a result of having to get them to fit in to a non-AT board and and when it is vertical it is enough pressure to stop the serial port working. It is the weirdest problem I have ever seen and it is driving me crazy! I wish I had a proper AT case.

Does your ATX case have the proper AT board mounting holes, if not you may want to invest in a drill to make new stand off holes for the AT Board. But most older Pre 2002 Case have stand off holes predrilled for Baby AT

Arctc Silver 5 is conductive, has a limited lifespan, and is messier to clean up. I recently stopped using it because of these reasons, especially because Arctic MX-4 tests about the same as Silver and does not have these issues.

clueless1 wrote:

Arctc Silver 5 is conductive, has a limited lifespan, and is messier to clean up. I recently stopped using it because of these reasons, especially because Arctic MX-4 tests about the same as Silver and does not have these issues.

I have some stuff that cleans it off perfectly. It has always worked really well for me.

candle_86 wrote:

rick12373 wrote:

I have a heat sink and fan on there, but without thermal paste. I might put some on, I have some Arctic silver 5 somewhere. Although, I am still having a really weird issue, which apparently is not related to the heat of the CPU. I have this 486 built in to an ATX tower. It was hard to get it to fit but with a bit of tinkering I got the card and motherboard seated. But when the tower is on it's side, so that the MB is horizontal my serial mouse will work. when I put the tower vertical it does not. All of the cards are in there firmly without any wobble. I can only think that the board and/or cards are slightly twisted in some way as a result of having to get them to fit in to a non-AT board and and when it is vertical it is enough pressure to stop the serial port working. It is the weirdest problem I have ever seen and it is driving me crazy! I wish I had a proper AT case.

Does your ATX case have the proper AT board mounting holes, if not you may want to invest in a drill to make new stand off holes for the AT Board. But most older Pre 2002 Case have stand off holes predrilled for Baby AT

It did have the proper mounting holes, but the cards were difficult. With some of them the bracket was to long and also they didn't seem to line up perfectly.

noshutdown wrote:

einr wrote:

A DX2/66 though is the very last processor I would run without a heatsink. As soon as you're into DX2/80 or DX4/100 territory it's heatsink at least and probably a small fan, too.

dx2-66 is actually the hottest 486 from intel, generating more than 6 watts, while dx4-100 generates about 4watts.

as for dx2-80, 5v models exist from amd and cyrix, generating 8 watts as the hottest 486 in the world. but they are pretty rare and 3.3v ones are more common, which generates around 3watts.

Huh, that's interesting. My Intel DX4/100 has both heatsink and fan and I don't think I've ever seen a DX4 without cooling, but that doesn't mean what you're saying isn't right 😀

Just out of interest, how hot does the DX50 run? I find a figure of max 5-ish watts on CPU-world but it's not clear if that's referring to the original 1 µm version or the revised 0.8 µm one. I would think that the older DX50 on the 1 µm process would be really hot, if not the hottest Intel 486 then certainly close..?

clueless1 wrote:

Arctc Silver 5 is conductive, has a limited lifespan, and is messier to clean up. I recently stopped using it because of these reasons, especially because Arctic MX-4 tests about the same as Silver and does not have these issues.

AS5 is capacitive but harmless unlike the liquid metal compounds that cause some serous grief should it come in contact with aluminum. I switch to gelid gc-extreme years ago and there is no cure time, cleans up with ease.

nforce4max wrote:

clueless1 wrote:

Arctc Silver 5 is conductive, has a limited lifespan, and is messier to clean up. I recently stopped using it because of these reasons, especially because Arctic MX-4 tests about the same as Silver and does not have these issues.

AS5 is capacitive but harmless unlike the liquid metal compounds that cause some serous grief should it come in contact with aluminum. I switch to gelid gc-extreme years ago and there is no cure time, cleans up with ease.

You're right...my mistake. But according to Arctic Silver themselves,

Not Electrically Conductive:
Arctic Silver 5 was formulated to conduct heat, not electricity.
(While much safer than electrically conductive silver and copper greases, Arctic Silver 5 should be kept away from electrical traces, pins, and leads. While it is not electrically conductive, the compound is very slightly capacitive and could potentially cause problems if it bridges two close-proximity electrical paths.)

That was the point I was trying to make. You have to be careful of this stuff getting somewhere and causing an unintended bridge.

clueless1 wrote:

You're right...my mistake. But according to Arctic Silver themselves, […]
Show full quote

nforce4max wrote:

clueless1 wrote:

Arctc Silver 5 is conductive, has a limited lifespan, and is messier to clean up. I recently stopped using it because of these reasons, especially because Arctic MX-4 tests about the same as Silver and does not have these issues.

AS5 is capacitive but harmless unlike the liquid metal compounds that cause some serous grief should it come in contact with aluminum. I switch to gelid gc-extreme years ago and there is no cure time, cleans up with ease.

You're right...my mistake. But according to Arctic Silver themselves,

Not Electrically Conductive:
Arctic Silver 5 was formulated to conduct heat, not electricity.
(While much safer than electrically conductive silver and copper greases, Arctic Silver 5 should be kept away from electrical traces, pins, and leads. While it is not electrically conductive, the compound is very slightly capacitive and could potentially cause problems if it bridges two close-proximity electrical paths.)

That was the point I was trying to make. You have to be careful of this stuff getting somewhere and causing an unintended bridge.

Besides that I just don't like wasting expensive compound, the way people apply it sometimes is cringe worthy even oems sometimes put way too much.

I've never liked AS5, it was messy, difficult to clean, to me it wasn't nearly worth the fuzz it got. I simply used some MX-2 or so? I also got some cheaper stuff which is perfectly fine for quick tests and very old chips like P1 and earlier.

My DX4 got one of those taller passive spiky HSs along with one of those z-clips (I still don't know what to call them 🤣) and the heatsink would start to get uncomfortable to touch after heavy use for an hour or longer (no burns though, but it did get me worried a bit). It did take a lot of time for the heatsink to get hot though.

I can't remember from top of my head if the CPU is Intel or AMD though, I'd have to see if I mentioned it somewhere before or just take off the heatsink and have a look.

Another final solution for heat problems. Is to take a big aluminium chipset heatsink from a socket 478/775 board and glue it to a 486 cpu. Mind, this is a final solution, will only work for Intel dx2-66 and down, and it will sort of ruin the looks of an old vintage cpu. It will not destroy it though. I am thinking of those thermal paste/glue products. It's possible to get it off. Though hard to clean off.

rick12373 wrote:

Do I need a heat sink or a heat sink/fan for a 486 DX2 66Mhz? I did not think it was necessary. But I was experiencing a weird issue where the mouse was not working any more. The machine had been on for a while. When I touched the CPU it was quite hot. I left the machine off for a while and turned back on and the mouse was working again. Weird.

From my test the DX2 66Mhz run quiet hot with and without heatsink. The Overdrive DX2 66Mhz has one stock and still it seems runs really hot.

Well AS5 isn't the best anymore, these days for removable paste its anything with crushed diamond, and I love that stuff 🤣

Running a nice small heat sink and fan which seems to do the job. The issue with the mouse not working was solved by one of two things I did. At the moment I am not sure which one it was 😕 . I moved the graphics card and I/O card to different slots and I am using a different mouse. So it could be that there was a loose connection in the mouse cable or something to do with the cards. Anyway, I am going to save some money and get a real AT case from eBay or something. I am fed up with messing around with this ATX case.