View Full Version : CPU fan or heat sink for AMD 486DX2/80?

September 14th, 2009, 04:28 PM
I picked this up recently and thought it was a little unusual that it didn't have a heat sink or fan (these usually had fans?). I definitely need one for any prolonged use, correct?


This question is literally answered a couple threads down. Apologies; classic case of not searching before posting.

Anonymous Coward
September 15th, 2009, 06:28 PM
I don't have any experience with the DX/2-80, but I do know that the AMD DX/2-66 runs quite hot. The DX/2-80 is a 5V chip is it not? That would make it the fastest 5V 486. You'd be brave to run it without any cooling provisions.

September 15th, 2009, 09:04 PM
The DX/2-80 is a 5V chip is it not? That would make it the fastest 5V 486...

No, the AMD 486DX2-80 was 3.3V. And the highest speed 5V of a 486 class was a 486DX4-100. The POD63 and POD83 (¨Pentium Overdrive for 486¨) were also 5V.

Ole Juul
September 15th, 2009, 10:10 PM
IBMMuseum: No, the AMD 486DX2-80 was 3.3V. And the highest speed 5V of a 486 class was a 486DX4-100.
Perhaps it is wrong, but the Wikipedia page (http://en.wikipedia.org/wiki/Intel_80486DX4) says:

The IntelDX4 microprocessor is mostly pin-compatible with the 80486, but requires a lower 3.3V supply.
The page mentions the 100MHz as being either 3x33.3MHz or 2x50MHz, but doesn't mention any voltage difference between the 75MHz and the 100MHz. I would be interested in sorting that out because I have a machine which identifies itself as 486DX4/s100 to my diagnostic software. I haven't had it open in a couple of years, but I'm going to go do that shortly.

September 15th, 2009, 10:49 PM
I'm running a 3.3V Amd SV8 486/100 without fan but with big heatsink- but at 66 Mhz.
That just about goes.

Depends on the airflow in the case- for 80 mhz I would use a fan or add a bigger, quieter case fan in the region of the heatsink.

Ole Juul
September 15th, 2009, 11:25 PM
I opened up the box and I can't tell by looking at the chip what the brand is, but by the jumpers, it should be an AMD. Also, by the jumpers it is set to 3.4V. This is (was) a good working machine, by the way. :)

So, the AMD486DXs100 is 3.4volt, and for the main purpose of this thread, it has a small heat sink and a small fan.

September 15th, 2009, 11:34 PM
The 100 Mhz is 3,3V - but depending on what your VRM supports, it will run at 3,0V underclocked too, most of the time.

The 80 Mhz is 3,3V core / 5V I/O

Ole Juul
September 15th, 2009, 11:40 PM
Thanks Jorg, I was just about to post on that when you butted in. :) Here is a list:

September 16th, 2009, 12:10 AM
The 486DX4 is still in production for industrial applications requiring moderate embedded processing capability.

Wonder how much they run...

EDIT: Here are some links to pages that have some very nice tables on the settings/voltages for Intel (http://en.wikipedia.org/wiki/Intel_80486#Models) and AMD (http://en.wikipedia.org/wiki/Am486) 486 chips

Ole Juul
September 16th, 2009, 01:12 AM
Since this thread is a bit redundant anyway, I'll post this OT link which I found in the process of looking up processors. :) It has entries like "1991 - May - At the Comdex show, Intel introduces the 20 MHz i486SX microprocessor. The i486SX is like the 486DX, but without the math coprocessor. Price is US$527." and more to the point in this thread "1994 - September - Advanced Micro Devices ships its Am486DX2-80 40/80 MHz processor. Price is US$266 in 1000 unit quantities." In other words, a really detailed chronology of microprocessors, 1958 to present. There are other chronologies there too. http://www.islandnet.com/~kpolsson/refs/comprefs.htm Copyright Ken Polsson (http://www.islandnet.com/~kpolsson/) but OK to link. Check out his home page for many other chronologies such as Corvettes, Coins, and Video Game Systems etc.