486 CPUs
Posted by VaelorsKeep@reddit | vintagecomputing | View on Reddit | 45 comments
I need some insights about 486 CPUs. I'm going to acquire/build a 486 soon for the first time in 30 years and I want to make sure I get it "right".
Over the last couple of decades I've heard a lot of people say with passion that the 486 DX2/66 chip was the best 486 CPU for reasons, better in fact than its successor, the DX4/100. And I've heard a lot of people say that that's just nonsense. I've never really followed the argument long enough or closely enough to figure out what the real pros and cons are, but now that I'll be obtaining one or the other again myself for a build, I figure it's time I found out which one is the superior chip and why. So I'd like to hear from some other ancient PC builders like myself who still know/remember things like that about why I should pick one or the other. 30 years ago when I built my last 486 I was a teenager, and less concerned about fine tuning specs as I was about building a PC that booted up and played my games without crashing.
I'd love to hear any advice, info, or suggestions you can give me on the topic.
CobraG0318@reddit
And 5x86 133 CPU. For speed and general stuff.
Other CPUs, like the 486dx2 and such if you'll want to slow it down for older titles, but maintain a decent speed for newer titles.
Pentium overdrive 83, if you just gotta run pentium optimized stuff, but all you have already is a 486 motherboard, though this CPU is expensive. In fact more expensive than getting a proper pentium motherboard and CPU of the era together. So only recommended if you're some sort of quirky enthusiast.
486sx, not much point unless you're desperate, or quirky. I'll add in 486sx2, as well. Worthwhile as a collector's item since they're rare, but there are better things to put in a functioning system
487, I add since they're just a 486dx relabelled. I think has an extra pin to disable an onboard 486sx CPU. Probably not worth it as they're pretty uncommon, and I don't think come in clock multiplied versions.
Also, check your motherboards voltage support, as some of the above CPUs are 3.3v. If your motherboard doesn't supply 3.3v or is strictly a 5v board, you'll have to use an "overdrive" version of the CPU. Or an evergreen or Trinity powerstacker in case of the 5x86.
486slc, slc2, sxlc, sxlc2 you won't have to worry about these, as they're soldered on to theirbmotherboards. I'd also not recommend them, unless you're really board and open to experimentation. They will never perform as well as most any of the above CPUs. Maybe a 486sxlc2 66 might keep up with a 486dx 33 or something at best. They're basically a 386 CPU, given a 486 instruction set, and soldered onto a modified 286 motherboard. Kinda an absolute shitshow. Which is why I got one. Lol.
siliconlore@reddit
The speed of the 33MHz clock-trippled DX4/100 is about 90% of a 60MHz Pentium at debut. I think there was also a 25MHz clock-quadrupled version but I never saw one.
The speed of the DX4/100 felt at least twice that of a DX2/66. However, the DX2/66 really was a sweet spot where the 486 started to outpace many other CPU models and felt faster than many UNIX workstations of the day.
I specifically bought a DX4/100 notebook because it was about $1000 cheaper than a Pentium 60 notebook and it ran almost as fast.
lutiana@reddit
The DX2-66 was probably the most popular of the 486 CPUs, so there are a ton of people with nostalgia for this chip. But better than the DX4-100? What does "better" mean in this context? The DX4 was more performant than the 66, I mean, it's nearly 1.5x the clock speed, which back then made a big difference.
The DX4 was released very late in the 486 life cycle, possibly after the first pentium, and since the pentium was a literal game changer, people tended to go for that over the DX4.
The "best" cpu for your build is the one that matches your goals. If you are looking to build something perdiod correct and matching the predominant 486 of the time, then go with the DX2. If, on the other hand, you actually want to use is, and prefer the best 486 performance, then go for the DX4-100, or if you can find it, the AMD AMD Am5x86.
Personally, I'd suggest starting with the board, once you have you that you can work out which CPUs work on said board and pick the one that will best match your goals and go from there.
DrNick42@reddit
Depends. Do you want a faster or a slower 486?
DX2-66 is undoubtedly the most iconic, but also possibly the least useful IMO. It's just quick enough for some speed sensitive games to be annoyingly too fast, but not really fast enough to play more demanding games at anything like good frame rates. But, if you want a DX2-66, get that.
Otherwise I'd be inclined to get either a much slower system for DOS platform games and speed sensitive titles - maybe a 486-25 or 386-33. Or go the other way and get something that can at least play doom at respectable frame rates. DX4-100 is obviously better for this but why not go the whole hog and get a 5x86-133, which is the quickest 'official' 486-class system.
bigbigdummie@reddit
CPU cache is going to mean more than DX2-66 versus DX4-100. Get as much cache as you can.
Im_100percent_human@reddit
Both Cyrix and AMD made a 486DX2-80. AMD made a 486DX4-120. Personally, the AMD 486DX4-120 would be my choice as GOAT 486 processor.
sw1ss_dude@reddit
the GOAT 486 should be the Cyrix 5x86-120GP, which was not really common, but very innovative hardware wise, and beat everything clock to clock. But overclocking was poor, so an AMD 5x86 at 160 Mhz was actually faster
Im_100percent_human@reddit
Is it fair to call the Cyrix 5x86 a 486? It had a lot of advanced functions that the 486 lacked, like branch prediction and more advanced pipelining (far less advanced than Pentium, though). While it is socket 3 compatible, so was a version of the Pentium Overdrive, which none of us would call and "486."
Cyrix 5x86 was definitely superior to the AMD 486DX4-120, but I, personally, don't consider it a 486.
sw1ss_dude@reddit
Correct, it‘s basically a cut down Cyrix 6x86 so hardly a real 486 anymore.. however the AMD 5x86 is just a fast 486.
Im_100percent_human@reddit
Interesting... I didn't really remember the AMD 5x86. There seems to be a lot of overlap with the AM486 line, which would, essentially, be the same chip with different model names/numbers.
It appears that the AMD 5x86-160, was a 40Mhz FSB with a 4x multiplier.... The AMD 486DX4-120 was also a 40Mhz FSB with a 4x multiplier, but they claimed it was 120Mhz equivalent. I wonder if they are really the same.... If the AMD 5x86-160 is faster the than AMD 486DX4-120, It would be the GOAT 486.
These F'n chip makers made nothing simple.
sw1ss_dude@reddit
It appears that the AMD 5x86-160
Officially there was only AMD 5x86-133, but they could be easily overclocked from 4x33 to 4x40. But even the AMD 5x86-133 was faster AMD 486DX4-120
here is an exhaustive benchmark comparison if interested
https://www.vogons.org/viewtopic.php?t=28470#:\~:text=Ultimate_486_Benchmark_Comparison.pdf
Kitchen_Part_882@reddit
If you go with a VLB motherboard, keeping the FSB at 33MHz will avoid a lot of the timing related issues some cards of the era had, either a DX2 66 or a DX4 100 would achieve this.
I believe some of the later PCI boards had a separate (asynchronous) clock so sidestepped the issue when using a 40 or 50MHz CPU clock.
jtsiomb@reddit
Here's a few things that come to mind, how relevant is each of those in your case, you be the judge:
in terms of CPU performance, the DX4/100 is unquestionably faster. But the 4x multiplier means the bus speed is 25mhz vs the 33mhz of any DX2, which makes bus transfers (critically memory access) slower. Maybe it's better to go for the DX2 80, which is both faster, and also overclocks the bus to 40mhz, although you might encounter trouble with marginal peripherals.
CPUs 80mhz and higher need a motherboard that supports 3.3v, so they may not be as compatible as earlier parts.
unless I'm mistaken intel only ever got as far as 66mhz, for higher clocks you need to go to AMD. I have a vague lingering perception from the time, that intel was preferable. It certainly was against cyrix, but AMD was probably on par for the 486 (they lost the plot later with the pentium), so I don't think it matters.
The 486 dx/4 100 eats up more power, runs hotter, and absolutely needs a heatsink and fan (even a tiny one). The dx/2 80 needs just a heatsink. The dx/2 66 need neither.
starcube@reddit
The DX4 has a 3x multiplier not 4. The fastest DX4 ran at 100MHz.
mojoxer@reddit
The DX4-100 also had a variant that ran at 100MHz with a 50MHz FSB.
sw1ss_dude@reddit
AMD had a DX4-120 (3x40 Mhz)
starcube@reddit
We're talking about Intel.
sw1ss_dude@reddit
But the 4x multiplier means
Fun fact: the DX4 had 3x multiplier , so it should have actually called DX3
jtsiomb@reddit
right, I forgot that. So scratch that downside.
ketsa3@reddit
Will not make a difference : they all suck.
Either_Ad_5641@reddit
Wasn’t the 5x86 133 the best choice, I’ve heard of people who played Fallout on it
sw1ss_dude@reddit
5x86 was only to give a cheap alternative to earlier Pentiums (up until P90 if overclocked), it was a drop in upgrade with existing 486 motherboards. From P100 there was no competition with 486 anymore
WingedGundark@reddit
DX2-66 being better than some other 486 is absolute bollocks. 486 CPU is exactly the same in all 486s CPUs, including SX which just lacks the FPU. Other differences are that enhanced models support write back L1 cache. DX4 CPUs are rated 3.3-3.45V, slower CPUs 5V. This means that you need the motherboard to support it, use voltage converter/interposer or then change the regulators on the MB. Some MBs had even connectors for external voltage regulators.
If you want the classic 486dx2 or dx4 build, I’d definitely go with a good and fast VLB chipset and motherboard and decent VLB graphics card. PCI chipsets such as SiS 85C496/497 offer the fastest 486 platform, support all 486 CPUs and in the best case scenario can be overclocked up to 200MHz, but I don’t find these being the golden age of 486s as they came out very late (1996-97) and were actually a low end budget option for Pentium systems.
What you want depends on your expectations. If you want that your Doom runs at or near FPS cap (35) most of the time, you want DX4 and at least decent VLB card. Doom starts to look smooth, on CRT at least, at around 25FPS and good DX2-66 with fast VLB graphics can achieve that often, but it will not run Doom optimally. This doesn’t mean that you should aim for the fastest 486 (and if you want the best DOS performance, I would look for Pentium in that case), but this is something you need to understand. No DX2 system is the ultimate 486 and no 486 is the ultimate DOS system.
I suggest you head to vogons.org. You will most likely find information for everything you need there and if not, why not make a thread of ylur own about your goals and you will get much better advice there. As it is a regular forum, your post also won’t get just buried after couple of days. Good luck!
ariadesitter@reddit
486 DX2/66 was the beast. the bottleneck for me was hard drive and video card. unless the entire system was updated i could barely tell the difference between DX2/66 and DX4/100.
plus weren’t there bus limitations too?
i mean i retrospect you can build the best pc for a specific time period but unless it has a cutoff date you end up creeping to newer and newer tech
myrsnipe@reddit
DX2 will play doom fine, duke3d will struggle somewhat and I would recommend a dx4 for it
Hot_Cheesecake_905@reddit
The DX2 is viewed as "superior" because it held the performance crown until the Pentium came out in 1993. The DX4 was released after the Pentium in 1994 and seen as a stop gap solution.
Objectively I think the DX4 is faster than the DX2, but if you're buying a 486, the DX2 seems like the iconic version of it for me. If you want something faster, you may want to consider an early Pentium?
sw1ss_dude@reddit
The DX4 was released after the Pentium in 1994 .
It was released after the Pentium 60/66 which was not really considered a success because of initial issues (heating/FDIV bug/performance). The P75 which was clearly superior to it, was released about half a year after DX4. The PC landscape changed extremely fast back then
BlackberrySad6489@reddit
I had both the dx266 and the dx4100. The dx4 was way better in my experience. But I mostly just played video game. Ran linux on it for a while.
secondhandoak@reddit
DX2 was most popular late 486 and frequently listed on the system requirements for popular games.
majestic_ubertrout@reddit
So, I think it's worth asking exactly why you're building a 486 machine and I think that can inform what the "best" choice is.
Some late 486 PCs can give an early Pentium a run for its money - some of the time. But in 2026 I'm not sure why you'd want one of those when you can pretty easily find a Pentium 2 ATX board with ISA, PCI, and AGP which will be miles ahead in performance and be much easier to work with. And you can do a board with a Aureal Vortex and ISA sound card along with a early 3D card (or more) for the best of both worlds in late DOS and Win98SE. The gap in ease of use between a 486 and early ATX board is much greater than the gap between that early ATX board and a modern system.
In 2026 the value of a 486 is that it gives you bare metal compatibility with the games and programs which don't play well with faster speeds, mostly from the era from 1993 and earlier. So I actually don't think raw speed is what you're really looking for since except for a few outliers like Strike Commander most of these don't need anything much beyond 33 Mhz. I personally run a 50 Mhz DX2 with a Turbo and find that turbo botton to slow down very useful.
chrisgreer@reddit
From what I remember (I believe there was also a dx50). In the dx2-66 the bus only ran at 33MHz. In the dx4-100, the bus was only 25MHz. The DX-50 was a 50MHz bus and chip. So depending on what you were doing, the lower clock speeds were actually faster. If you were just number crunching and doing things that lived mostly on the chip the extra clock speed really helped. If you have things that were using the bus the dx2-66 is probably better than the dx4-100.
http://brassicgamer.blogspot.com/2023/04/the-almost-definitive-486dx50-and-dx266.html?m=1
smpstech@reddit
DX2 is cheap and plentiful, it’s also well representative of the time, it’s what most enthusiasts had and experienced back then. For practicality’s sake, a cheap low end pentium will do anything a DX4 will do and more. Of course, there’s the cool factor of really maxing out a 486 and seeing what it can do, but it does come at a cost.
thehappiestotaku@reddit
I built a couple of dozen systems around that time, and my memory of this is that the DX4 was in fact better, but it was not necessarily worth the price from a pure performance standpoint.
I think if I was building today I wouldn't care so much about that, but back then it would have been a lot of questions about what you planned on doing with the system. You'll definitely want to have some form of cooling though, they get hot.
sw1ss_dude@reddit
depends on your goals, DX2-66 is more relevant historically, DX4-100 handles some games better from that era. Also cooling wise DX4/100 already needs some cooling where the DX2/66 is fine without..
Even more important question whether you are aiming to build a VLB or PCI based system. The most classic setup is a VLB based DX2/66 , where DX4 was already leaning more into the PCI era.
martijnonreddit@reddit
IIRC the DX4/100 was released after the Pentium 60 and was positioned as a cheap alternative to the latter. The Pentium basically destroyed everything that came before it and ended the 486 era.
sw1ss_dude@reddit
I think it was the AMD 5x86-133 which is technically a DX4 (where a DX4 is technically a DX3) . It had even P75 in the model number, to which it was comparable in speed (depending on who they tested).
aranar_tse@reddit
The DX2-66 is more consistent with the era. It was the goto solution to play Doom and run Windows 3.1. A DX4-100 was like the ultimate upgrade when you couldn't afford a full system replacement to get a Pentium.
Both options are quite nice. It all comes down to what you want to run and how easily you can find PCI or VLB cards.
fondow@reddit
You might as well rebuild something as close as what you had 30 years ago, if what you wish you had at the time.
Because I'm not sure there is a correct answer.
martijnonreddit@reddit
Yes! As a kid I was lucky enough for our family to have a 486 DX 33 with VLB which was already pretty badass. But if I were to build a system from that age now it would be a DX2/66 with an AWE3, which was basically my dream machine back then.
Js987@reddit
I‘m digging deep into my memory here from my own 486 days, but I think people preferred the DX66 because it was still 5V, which gave a larger variety of motherboard choices, but that’s just a vague recollection.
pinko_zinko@reddit
This was my experience when shopping around for mine. Motherboards are not easy to get now, especially if you get picky about things like PS/2 ports or VESA slots. Whatever you end up with will dictate the CPU, which is much easier to source.
Scoth42@reddit
The 66 was a sweet spot in power where it would run basically all the DOS games you wanted just fine while still being 5V and having wide compatibility with even the earliest 486 motherboards through the VLB and PCI ones. The 100+ ones were faster and "better" but started adding in complexity with voltages, motherboard support issues, different brand of chips that needed different support, etc etc while not really being faster enough to make late-era DOS games that a 66 wasn't enough for playable. Maybe if you held out for the some of the fancier 100+mhz AMD chips you might be able to play them, but they were their own complications.
If you want something you can slap together and it mostly Just Works, a 66mhz is going to be good enough for most peoples' uses. I have a 120mhz AMD version and love it, though it definitely took some tweaking to get good.
ZarK-eh@reddit
My Fathers 486 I swapped out a dx266 for an AMD 5x85-P75 and kept the original CPU.
*shrugs* get something and if ya dont likes it, change it. In other words have fun
sharpied79@reddit
AMD x5-133Mhz 😉
Immediate-Sink-8494@reddit
What's your goal with this sytem? What are you looking to get "right" about it?