Thinkpads Forum

This is something that might be of interest to anyone who collects classic computers, it's a Cyrix CPU upgrade designed to replace an Intel 386 DX chip with a Cyrix 486 clock doubled cpu. If installed on a 386DX-25 your computer will have a 486cpu running at 50mhz.

Back in the day these were nice upgrades and even though they don't have any practical applications today, it would really speed up any classic computer you might have in your collection.

I should have several of these packed away somewhere, but at the moment I've found two, brand new in sealed retail boxes. Here is a photo of what they look like...



I don't know if there will be any interest at all in these so I'm just going to list the two I found. They are designed to upgrade a 386DX25 but will work on slower or faster machines. It comes with a self adhesive passive heatsink (note that the intel 386 didn't require any heatsink at all, but if you're going to run it at 33/66mhz you'll probably want to use a heatsink with a fan, or devise a better method of attaching it to the die.

I'm going to start at $15 plus postage each, but you're welcome to make an offer. I can ship it in a flatrate envelope for $6, or if you don't want or need the original packaging I could put it in something smaller and lighter and ship it for about half as much. If I recall correctly the package includes the cpu chip, heatsink, cpu removal tool, and software to enable the internal cache memory if your bios doesn't support internal cache (if your motherboard supports 486DLC it will support internal cache, otherwise to take full advantage of the chip you'll need the driver installed.

I realize there may be no interest at all in these old gems so I won't be bumping this topic, but if there is someone here that enjoys old computers, here is a chance to wake them up a bit and price is negotiable as I really want to see these used, they aren't doing any good stuffed in a box somewhere.

I may also have a 286 to 386sx upgrade chip (if I can find it). and maybe even a 486 to 586 chip.

If no one here is interested I may try ebay, or just send it to gold recovery.

Moderator edit: Added a "PIC"-warning to thread title.

Wow! An awesome blast from the past! I remember drooling on these back around 20 years ago in an Egghead Software store! Back then I only had a 386SX/33 and little money. Took me a while to save up for a 1MB RAM (!!!) upgrade for it which doubled my RAM.

Agreed, I got a great deal on them about 20 years ago, most sold quickly but when they became obsolete I just packed the few remaining in a box and they have collected dust since. These are still sealed in the package and it occurred to me that they might now be old enough to have some value. If I had the time and space I would enjoy collecting vintage computers and playing (period correct) games on them and having a massively faster cpu chip that doesn't require any modification to install would be great... so I hope these find a good home.

The 386sx was a soldered chip but I think I might have a chip for that model too. In that case instead of replacing the cpu you snap the chip on top of the soldered cpu. The connection to the board was by contact only, but they did work well and I had one installed in my very first computer that could be called a "notebook", the IBM PS2 model L40sx. It was the grandfather of all thinkpads, a true notebook computer that used desktop cpu and ram. It had a 386sx20 and 2mb of ram if I recall correctly. I maxed it out to either 5 or 6mb of ram and 486sx2-40mhz (actually closer to an slc2, and when I installed a math co-processor FPU all my software recognised it as a 486DX 40mhz, however it was still limited by the 16bit memory bus that all 386sx used. The chip above is a full 32bit version and could easily run windows 95, and although windows 98 will object if you try to install without at least 66mhz (or perhaps 50mhz), it will run flawlessly on as little as 33mhz (off topic but it was a common trick when refurbing old computers to pull a 486DX33 chip and install a DX2-66 just long enough to install Win98, then swap the old cpu back and you're good to go).

ps. I'm going to post a few more classic parts here to see if there is any interest. I just found a brand new 2nd harddrive adapter for a thinkpad 760XD. Perhaps one of our collectors can use it.

WOW! I used to dream of this update many many moons ago. Never could afford it and decided to choose food over CPU....yeah I know I was young and stupid then. Food could have waited.

Cigarguy wrote:WOW! I used to dream of this update many many moons ago. Never could afford it and decided to choose food over CPU....yeah I know I was young and stupid then. Food could have waited.

Haha, I love this place.