I think the Intel rapid-cad is probably the "fastest" thing you can slap into a 386 but wont have any noticeable effect unless you are using math heavy programs.

But in all reality it would most likely be cheaper and easier to get a 486 if you need something faster than the amd-40

I want to build a fast 386 platform, I draw the line at the 132pin PGA slot mainboard, their are hybrids which contain a 486 socket as well but im not interested in them.

Its getting the most out of the platform that interests me, not a specific performance target as such.]

From what I can gather the DRX2 66 works on a 33mhz bus, the 50mhz on a 25mhz bus, I would'nt touch that.

Their are also Texas Instruments SXL2-50 but only on a 25mhz bus but with 8kb level 2 cache vs the cyrix 1kb, I would think the cyrix will still be faster

We have a few clock doubled chips in our 3dbench database, I believe they are 40 MHz models on SX-20 machines.

A 486DLC should have plenty of grunt, AFAIK they aren't that far behind a 486DX.

I owned a DRx2 33/66 for a while. It's really not a bad chip, but the 1k cache still holds it back. Overall, I found that the TI 486SXL-40 was faster (a 486DLC with 8kb cache). The best 386DX upgrades are the IBM blue lightning chips. Those have 16kb cache, and are about equal to a real intel 486 (except for FPU stuff).

I also owned a rapidCAD. Aside from being pretty rare, it's not worth it. While technically it is based on a 486 core, intel disabled all the good stuff (8kb cache and 486 instructions) so it hardly performs better than a 386 with integer math. FPU is another matter. I didn't really bench the FPU, but my understanding is that a clock doubled 387 may be just as good.

The 486SXL-40 is a mhz bus and not clock doubled? Would you think going for one of those would be better than a 50 or 60mhz clock doubled chip?

dirkmirk wrote:

The 486SXL-40 is a mhz bus and not clock doubled? Would you think going for one of those would be better than a 50 or 60mhz clock doubled chip?

It's not just the raw megaherzes that count. You can imagine that a clock doubled 2x20Mhz will be slower then at 1x40Mhz 😉

In my experience, a TI 486SXL-40 is faster than a DRx2-33/66 because it uses the 40MHz bus and because it has a larger cache. Though, the DRx2-33/66 isn't too far behind. Also, I think the Cyrix chip can be easier to get working. But overall both are somewhat of a pain in the ass. Be careful if you plan to use one of these chips on a system with a DMA SCSI controller.

The main problem that people have with the 486SXL chips is enabling the clock doubling feature. (The 486SXL-40 and 486SXL2-50 are actually the same chip, they just have different names for marketing reasons) I have actually used my 40MHz chips in clock doubled mode. However, in my opinion it is not useful as a single clocked 40MHz chip seems faster in most operations than a clock doubled 50MHz chip.

Whatever you choose, be prepared to play around.

Are you saying their are 2 486SXL chips? IE clock a doubled 20mhz and a normal 40mhz version?

The next thing is to find a decent mainboard, their are still those Contaq boards for sale on ebay which looks to be a good option however I would like a board that takes 16meg simms like my Soyo does, it would have been perfect if it had a PGA socket.

If you have a surface mounted 386SX then Evergreen made an upgrade using an IBM Blue Lightning chip. (Not related to the later 486DX Blue Lightning). It clips on over the top of the 386SX and is the fastest upgrade because the IBM used 16k cache in their chips. Those upgrades are extremely hard to find though and they don't fit into the 132 pin socket. For that you want a Texas Instruments chip. They have 8k cache, which is still better than the 1k in the Cyrix chips. You needed special software to activate the cache, though, as it wasn't recognized natively by the motherboards of the day.

You can get blue lightning chips for 132pin 386 sockets. Pretty much every company in the upgrade business made one. They're probably not easy to find, but they are out there. I highly recommend this upgrade if you can find it.

Realistically, a TI486SXL is probably going to be a lot easier to find.

There are 4 chips (technically two) in the TI486SXL family:

These two are for 386DX systems:

TI486SXL-40
TI486SXL2-50

These two are for 386SX systems:

TI486SXLC-40
TI486SXLC2-50

What I was trying to say earlier is that there really isn't a difference between 40 and 50MHz parts except for the label. The 40MHz parts contain the same clock doubling circuitry as the 50MHz parts. On either model, the multiplier is set to 1X by default, and software is required to enable clock doubling. This is different than the clock doubled cyrix chips, where the clock doubling is enabled by default and there is no possible way to disable it.

dirkmirk wrote:

I've a 386DX-40 and thought that would be the ultimate 386, then I heard about a Cyrix 486DLC/40 which I was about to purchase but they made more chips like the Clock doubled 66mhz 486DRX2? I assume these are pretty rare, does anyone have one and are they problematic or do they need certain mainboards to work? Any information would be very helpful.

I went through a similar 386 upgrade ordeal and have documented the progress here, 386 upgrade kits and the Transcomputer 486HPi - Am5x86-160 anyone? . I plan to update this link with benchmarks from all the fastest 386 upgrade options across several platforms. For now, I have showed how well an Am5x86-160 runs on a 386 motherboard.

Sorry for the late post, I was actually looking for my own thread while, which did not show up on google, but I came across this one which I felt could benefit from the attached thread. For some reason, when I type "vogons 386 upgrade kits" I do not see the above noted Transcomputer thread.