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Which 486DX2 processor is best

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barney

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Checking eBay, I see that there are several different brands of 486 processors (Texas Instruments, Intel, AMD, Cyrix and IBM). Is there any one brand that is the best? Will they all pretty much give me the same performance? Are there any brands which I should stay away from.

Also, for the system that I am putting together I am contemplating which speed CPU would be the best. I have narrowed it down to two: 486DX2-50 or 486DX2-66. Which one would be better for the era of games I am going to be playing (up to the mid 90's).

Barney
 
I think folks here have had their mileage vary with personal experiences. Mine were stay away from Cyrix chips. Intel is the most compatible usually but I generally liked AMD for overclocking. From what I recall Intel chips could be overclocked 1 step usually, AMD could usually handle 2, cyrix was 0 without us having lots of crashes.
 
barney:

I'm with barythrin on that. Maybe its because AMD had to try harder. While you at it, and it sounds like you haven't made your purchase yet, go for the big one. Shoot for the AMD 80486DX5-133. Its designed for 33 Mhz mobo's and in effect is setup to quadruple its output. As far as I'm concerned, it the king of 486's and can be had relatively cheap. That's just one man's prospective, wouldn't want to rain on your parade. BTW, my 5x86 easily overclocks to 150 Mhz.
 
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Actually, I have two of AMD 80486DX5-133 chips. They worked ok, except the turbo button would not function with it. Has anybody else out there had this same problem?
Agent Orange said:
barney:

I'm with barythrin on that. Maybe its because AMD had to try harder. While you at it, and it sounds like you haven't made your purchase yet, go for the big one. Shoot for the AMD 80486DX5-133. Its designed for 33 Mhz mobo's and in effect is setup to quadruple its output. As far as I'm concerned, it the king of 486's and can be had relatively cheap. That's just one man's prospective, wouldn't to rain on your parade. BTW, my 5x86 easily overclocks to 150 Mhz.
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The Cyrix and ST 486DX2s were identical, and I believe the TI DX2 was either based on the Cyrix design or was identical. Clock for clock, the Cyrix wasn't quite as fast as Intel or AMD. I ran some benchmarks to confirm it, and there definitely was a difference, but I don't remember anymore how big the difference was. There was enough price difference when they were new that budget-conscious people would buy them, but the only reason to buy them today, in my opinion, is if you're collecting chips. If you're actually going to use it, go with Intel or AMD.

The compatibility for Intel and AMD should be identical because AMD used Intel's microcode. Speed-wise, the DX2s should be identical too. The other thing to check is whether your motherboard has a 3.3v setting for AMD CPUs, because even the AMD DX2s ran at 3.3 volts. Intel and Cyrix DX2s ran at 5v. I know AMD's DX2s ran at 3.3v for legal reasons rather than technical (Intel sued AMD, and part of the settlement was that AMD wouldn't make 5v CPUs), so they may work fine at 5v, but I've never tried it myself.
 
IBM used Cyrix models. I forget if TI used Intel designs or Cyrix designs when TI was handling manufacturing for Cyrix.

I would go for a DX2-66. I don't remember very many software programs that needed the 25Mhz bus. Plenty of cheap motherboards couldn't handle the higher speed but that's a different problem. But the 66 could run on a bus set for 25Mhz so it gives you the most flexibility. Plus (at least for some Intel models), the DX2-66 came with a better heat sink. Actually, my quick check of Ebay suggests that the DX2-66 tends to be cheaper than DX2-50.

One thing to watch out for is that the later better 486 models required lower voltages and therefore won't work in an earlier 486 motherboard that only supplies 5 volts to the CPU. So, be cautious if buying an AMD 486 variant with 16kb of write back cache which should be the fastest DX2 model.
 
I do agree somewhat with the recommendation of the 5x86 133 as I once had one. However, I will have to toss in the IBM Blue Lightning as a contender.
 
barney said:
Actually, I have two of AMD 80486DX5-133 chips. They worked ok, except the turbo button would not function with it. Has anybody else out there had this same problem?
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That TURBO switch is kind of misnomer. It had most of its play with the 286 machines and I never though of it it to be very relevant. The only time you probably would ever need it was when some piece of old 8-bit software would stub its toe above 8-12 Mhz. You say that you couldn't get your TURBO function to operate properly. You might try 'reverse' logic on the mobo, i.e; OPEN instead of SHORTED or vice-versa. Also, I have a small program that will turn your cache and or off. Only works on the 486 (as far as I know - will not work on a full fledeged Pentium) and in effect with slow things down appeciatively. You're welcome to it.
 
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barney said:
Thanks for all the advice everybody. I think I will go with the Intel 486DX2-66.
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Within the Intel 486DX2-66 lineup, there is one version (S-spec SX955) that has the L1 cache settable to "Write-Back" rather than "Write-Through"...
 
Tell me a little about the "blue lightning". What makes it such a good chip?

Update: I did a little research and I found that the core is made by Cyrix. Doesn't Cyris have heating issues. I believe the early Cyrix (Pentium equivalent) had bad overheating problems.

deadcrickets said:
I do agree somewhat with the recommendation of the 5x86 133 as I once had one. However, I will have to toss in the IBM Blue Lightning as a contender.
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I have a Blue Lightning. It is a very efficient chip and surprisingly fast except for floating point. Great chip but IBM models tended to be soldered into motherboards making them difficult to place in other motherboards.
 
barney said:
Tell me a little about the "blue lightning". What makes it such a good chip?

Update: I did a little research and I found that the core is made by Cyrix. Doesn't Cyris have heating issues. I believe the early Cyrix (Pentium equivalent) had bad overheating problems.
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Not quite. There are two versions. One is IBM core based on Intel while other is Cyrix.
 
If it has to be a DX/2 I would get an AMD DX/2-80. 40 FSB speeds up video and HD transfers. An Intel 486 DX/2-66 is a classic for gaming if you don't like AMD.
 
The IBM blue lightnings were 386sx chips on crack mostly (386 bus) with no FPU and 16MB RAM ceiling. They ran cool with just a small heatsink (no fan), I have one board (IBM had to sell them surface mounted on a motherboard) in my collection. The Cyrix chips that overheated were the first batch of Pentium 166 equivalents (I had one new when they came out and returned it for a Pentium 133 because of overheating). Things got better with later Pentium class designs as far as heat goes, and there are quite a few different model types since Cyrix made them well into the Super Socket 7 era untill Cyrix was no more.
 
Unknown_K said:
The IBM blue lightnings were 386sx chips on crack mostly (386 bus) with no FPU and 16MB RAM ceiling. They ran cool with just a small heatsink (no fan), I have one board (IBM had to sell them surface mounted on a motherboard) in my collection. The Cyrix chips that overheated were the first batch of Pentium 166 equivalents (I had one new when they came out and returned it for a Pentium 133 because of overheating). Things got better with later Pentium class designs as far as heat goes, and there are quite a few different model types since Cyrix made them well into the Super Socket 7 era untill Cyrix was no more.
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Wasn't the 386 based one actually the Blue Lightning 1 and not the later 2 version?

http://cpu-museum.de/?m=IBM&f=486
 
There are a couple Intel DX4's that support the 2x multiplier.
I'd recon the fastest would be the Intel DX4 which supports Write Back, but I'm not sure if there ever was a PGA Intel DX4 WB made that supports the 2x multi.

Link to a list of Intel DX4's along with their supported multi's
http://en.wikipedia.org/wiki/Intel_80486DX4

But the question is:What do you need a DX2 for?
Do you need 5v or is 3.3v also ok?
 
3.3 V is a lot cooler- if the mainboard supports it, take that.
What mainboard is it (VLB?)

I'd just take an intel or amd DX2/66, or an AMD DX4/100 (3x33mhz).
Agree with above, stay away from 50 Mhz bus, keep it at 33, just avoiding trouble.
 
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