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First post, by appiah4

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I will put together a high-end 1995 PCI 486 and I can't decide between an Intel 486DX4-100, AMD 5x86-133 and a Cyrix 5x86-100. Yes I am spoiled for choices, but what are the pros and cons of these CPUs? I will be dual booting DOS/Windows3.x with OS/2 Warp 3..

Retronautics: A digital gallery of my retro computers, hardware and projects.

Reply 1 of 32, by Anonymous Coward

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All of these CPUs are pretty much equal at their rated speeds (Assuming the DX4 is the &EW version) . The AMD has the advantage of being able to overclock to 160MHz in most cases, which gives it the edge in integer performance. It also runs the coolest of the three because it's made on a .35 micron process. The Cyrix 5x86 has the best FPU performance of the three, but it also consumes the most power. The 100MHz parts can sometimes overclock to 120MHz, especially if you have the IBM version. These need a fairly advanced 486 board to really shine though. The ones that use stepping 1 revision 3 (S1R3) cores are also said to be stable with branch prediction running 32-bit code. The Intel DX4 is not terribly overclockable, but on the rare occasion you can get them up to 120MHz, which puts them in about the same league as the AMD 5x86 @ 160. I think I heard that intel DX4 might also have a few Pentium instructions, but I'm not sure how this would be useful.

What it really comes down to is if you care more about integer or floating point performance, and how easy it is to overclock the CPUs you have on hand. I think all of them are pretty good choices though.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 2 of 32, by appiah4

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The DX4 is an &E revision so WT only. I also have an Am486 DX4 SV8B but Im not sure if WB 8K would trumo 16K WB..

Also the Cx5x86 is an IBM chip but I dont plan to OC anything..

I doubt FPU will be critical for me so Am5x86 I guess?

Retronautics: A digital gallery of my retro computers, hardware and projects.

Reply 3 of 32, by Intel486dx33

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I just built a 1993 486dx4-100 computer with some of the fastest parts from 1993.
It has a VLB motherboard and 2mb Cirrus logic video card, 16mb ram, sound blaster 2.0.

It plays old DOS games great but if you cant to play modern DOS games with good performance So then you need a 1st gen Pentium.
LGR did a video about this.
https://youtu.be/jISmJG8QK0A

A 1st gen Pentium 75. Should be good enough.
Up to 133mhz appears to be period correct for 1995.

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Reply 4 of 32, by appiah4

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I know what Pentium is period correct for 1995, I have a Pentium 133 1995 build already. I am trying to pick a high end 486.

Retronautics: A digital gallery of my retro computers, hardware and projects.

Reply 5 of 32, by jesolo

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This might make for some interesting reading material: The Ultimate 486 Benchmark Comparison

I do agree that, for a 486, floating point performance should not really be a deciding factor.
From a gaming perspective, very few games (that could run satisfactory on a 486) made use of the FPU and would run just as well on any of these CPU's.
My choice is probably the AMD 5x86-133 (although, my plan is to actually build up 486 systems with all 3 CPU's, just for fun).

EDIT: You didn't mention how much RAM your PC has. If you intend on running OS/2 Warp 3, make sure you have sufficient RAM.

Last edited by jesolo on 2020-04-30, 19:26. Edited 3 times in total.

Reply 6 of 32, by mpe

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I'd choose Intel DX4-100. It feels like a proper 486 high-end for me.

In my opinion 5x86's are Pentium wannabees released as value propositions when the platform wasn't hot any more. Hard to associate "high-end" with them. For sure they are faster that DX4, overclockable, etc. But since you have the P133...

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Reply 7 of 32, by 2Mourty

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I've always enjoyed my cyrix 5x86 120. I have one of the blue ibm ones. Doesn't need a buzzy little fan like the POD83, and I can defintley feel a difference from the dx2/66 that I had before it. Since you don't plan on installing win95 though I'm guessing all of those cpu's will feel pretty snappy.

Reply 8 of 32, by CoffeeOne

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Anonymous Coward wrote on 2020-04-30, 15:28:

I think I heard that intel DX4 might also have a few Pentium instructions, but I'm not sure how this would be useful.

The intel DX4 had a fast integer multiplication (5 clock cycles). Unfortunately I can't find any good links now, where that is documented.

Reply 9 of 32, by CoffeeOne

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appiah4 wrote on 2020-04-30, 16:13:

The DX4 is an &E revision so WT only. I also have an Am486 DX4 SV8B but Im not sure if WB 8K would trumo 16K WB..

Also the Cx5x86 is an IBM chip but I dont plan to OC anything..

I doubt FPU will be critical for me so Am5x86 I guess?

I would go with the Cyrix, it is more "freaky", and not so common than the Amd 5x86.

Reply 10 of 32, by Intel486dx33

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He said he already has a Pentium computer.
So it all depends on his motherboard if it can support 5x86 CPU.

Back in 1993 computer companies where sell this build as a multimedia computer but it was under powered.
486dx-33
4mb ram
64kb. Cache.
ISA motherboard
Sound blaster 16 or Media Vision PAS16 sound card.
2x CD-ROM drive.
170mb hard-drive

———————————————
Like i said. This build should have been the minimum.
486dx2-66
8mb ram but 16mb in max.
ISA sound card
ISA motherboard but VLB could be faster.
256kb cache, 512kb cache does not provide much more performance improvement.
4x CD-ROM drive or faster.
210mb hard drive up to 410mb.

I think it was smart for Intel to skip the 5x86 CPU because it really does not provide enough of a performance boost over the 486dx4-100

The Intel Pentium Overdrive is what you want but then it will no longer be a 486 computer.

So, the Intel 486dx4-100 overdrive CPU was manufactured in 1994 and will workin most 486 computers.
Just set your jumps up for a 486dx-33 CPU.

Reply 11 of 32, by 2Mourty

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Intel486dx33 you are completely right. What you say makes the most sense and will probably be a completely stable computer. (If there is such a thing for a socket 3 pc) I just like punishing myself and playing with my freaky cyrix cpu. I lucked out and picked up a lucky star socket 3 motherboard that supports every socket 3 cpu I know of ( I was lucky because I didn't know a lot about 486 motherboards back in the day)

Reply 12 of 32, by Intel486dx33

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appiah4 wrote on 2020-04-30, 15:02:

I will put together a high-end 1995 PCI 486 and I can't decide between an Intel 486DX4-100, AMD 5x86-133 and a Cyrix 5x86-100. Yes I am spoiled for choices, but what are the pros and cons of these CPUs? I will be dual booting DOS/Windows3.x with OS/2 Warp 3..

I usually chose a theme as a build.

All Intel or AMD or IBM.

So for IBM you should start with an IBM computer and then apply upgrades using IBM components.

Reply 14 of 32, by PC-Engineer

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All three CPUs are very close in their performance, depending on the application.
The Am5x86 is the fastest of this three, but only a simple 486 with a upgrade in cache (16kb WB)
The intel DX4 has some improvements over regular 486 like a better integer multiplier and a better compatibility for clock sensitive applications and the 16kB cahce
Both intel and AMD 486 take zero benefit of the L1 WB mode with 2nd level cache
The Cyrix 5x86 takes profit from L1 in WB and has a stronger FPU
In general with socket3 boards you have a high chance of DMA problems with L1 WB

The iDX4 arrived the market in early 1994 and was highend at its arival with nearly the same price as the Pentium
The Cyrix and AMD 5x86 arrived the market late in 1995 as a low budget competitor to the Pentium

In my experience the 20% overclocking of PCI to 40MHz causes sporadic instabilities with IDE and SCSI controller and in my case (Chaintech 486SPM) with a Diamond Monster (Voodoo1) behind a Diamond S3 968 (with applied memory remapping). For a 40MHz FSB i would recommend a VLB system.

1994/1995 - Socket3 - ASUS SV2GX4 / POD 100MHz / 64MB / SCSI - Windows 95

Reply 15 of 32, by jheronimus

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I'm playing around with an AMD 5x86@160 VLB system right now. I also have a quite nice VGA card for it (an ARK Logic ARK1000VL), so it's kind of high-end (though lacking fancy storage at the moment).

For me it's the only platform where I think it's really fun to tweak the hardware on a fairly low level — e.g., messing with BIOS settings, trying various drivers/software enhancements/OS settings. So if this is what you're after, AMD is a performance option and Cyrix might be a more interesting option because it's more exotic.

But if I take your topic name at face value, there really is no such thing as a "high-end 1995 486 build". My build, for instance, is a pure 1995 machine, but really is more of a machine for someone who couldn't afford a Pentium, and thus, tried to squeeze everything out of an outdated platform. It's like calling Tualatin 1400 a "high-end 2001 Pentium 3" or AMD K6-3+ a "high-end 2000 Socket 7". Just doesn't make sense.

Like others said, a DX4 is the closest thing to a high-end 486. It existed alongside a much more expensive Socket 4 Pentium but could still beat it in most games. So technically, DX4 is still mid-range. The last high-end 486 would really be a DX2 😀

Otherwise, I think a 486 build is defined by your choice of motherboards more than anything. Do you want VLB or PCI? Which CPUs does your board support?

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Reply 16 of 32, by jesolo

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Intel486dx33 wrote on 2020-04-30, 21:34:
He said he already has a Pentium computer. So it all depends on his motherboard if it can support 5x86 CPU. […]
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He said he already has a Pentium computer.
So it all depends on his motherboard if it can support 5x86 CPU.

Back in 1993 computer companies where sell this build as a multimedia computer but it was under powered.
486dx-33
4mb ram
64kb. Cache.
ISA motherboard
Sound blaster 16 or Media Vision PAS16 sound card.
2x CD-ROM drive.
170mb hard-drive

———————————————
Like i said. This build should have been the minimum.
486dx2-66
8mb ram but 16mb in max.
ISA sound card
ISA motherboard but VLB could be faster.
256kb cache, 512kb cache does not provide much more performance improvement.
4x CD-ROM drive or faster.
210mb hard drive up to 410mb.

I think it was smart for Intel to skip the 5x86 CPU because it really does not provide enough of a performance boost over the 486dx4-100

The Intel Pentium Overdrive is what you want but then it will no longer be a 486 computer.

So, the Intel 486dx4-100 overdrive CPU was manufactured in 1994 and will workin most 486 computers.
Just set your jumps up for a 486dx-33 CPU.

I think the main reason why the 486DX-33 was more "mainstream" back in 1993 was purely because of price - as a matter of fact, by August 1995 (when Windows 95 was released), many people still had 386 systems. So much so that Microsoft stated that the minimum requirements to run Windows 95 was a 386 CPU with 4 MB of RAM.

Speaking from personal experience, I actually bought my very first computer towards the end of 1993 - earlier that year, as I recall, some factory in Taiwan burned down and memory prices went through the roof.
At that point, I had to choose between an Intel 486DX-33 or a Cyrix 486DLC-40 (with its math co-processor). Having very little information (no internet back those days), I went for the Cyrix, but in hindsight, should have gone for the Intel 486DX-33.
My computer only had 4 MB RAM, floppy, 16-bit Tseng Labs ET4000 ISA card and a 170 MB hard drive, but no CD-ROM and no sound card (the latter I could only afford a year later).

Reply 17 of 32, by Anonymous Coward

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Do you remember any details about the factory which burnt down? I've been trying to find a news article about it without any luck so far.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 18 of 32, by jesolo

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Anonymous Coward wrote on 2020-04-30, 23:18:

Do you remember any details about the factory which burnt down? I've been trying to find a news article about it without any luck so far.

Unfortunately, that's all I can recall, but I think it happened sometime in the middle of 1993.
It's just one of those things that stuck in my mind, because the memory was very expensive - I paid something like $140 (using 1993 exchange rates) for 4 MB of RAM (4x 1 MB of 30 pin simms). The going rate was more something like $170, but the one guy managed to get some simms for me for a cheaper price.
Might not seem like much today, but back in 1993, that was quite a lot of money to pay just for your computer memory. I was hoping back then to be able to buy 8 MB of RAM, but it just went beyond my budget.

Reply 19 of 32, by gdjacobs

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jesolo wrote on 2020-04-30, 22:54:

Speaking from personal experience, I actually bought my very first computer towards the end of 1993 - earlier that year, as I recall, some factory in Taiwan burned down and memory prices went through the roof.

It was at Sumitomo Chemical in Japan.
https://www.chicagotribune.com/news/ct-xpm-19 … 0189-story.html

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