I am thinking of building an era appropriate early/mid-2000s gaming PC. One requirement is that the CPU should not support x86-64 instruction set, only the 32-bit instructions can be used.

My guess is that the best CPU that fits the criteria is Gallatin-based Pentium 4 Extreme Edition. I can find information about 4 models of such CPU: 3.2 GHz (mPGA478B), 3.4 GHz (mPGA478B), 3.4 GHz (LGA775) and 3.467 GHz (LGA775).

Was the last model in the list the most performant "32-bit only" x86 CPU? If not, what was?

  • 5
    @tpimh I'm curious, why the restriction? While I agree, the step from 32 bit by default systems to 64 bit by default systems was a big one, but in the x86 desktop world, it was a pretty gradual shift: People bought amd64 CPUs and then used 32 bit Windows on them (and that still happens in other areas!) – simply because there wasn't that much upside to using a 2GB RAM system with a 64 bit address space, and because all 64 bit x86 (to my knowledge) are perfectly valid, compatible 32 bit x86 CPUs until you switch to 64 bit mode in software. Apr 6 at 10:47
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    @MarcusMüller: "all 64 bit x86 (to my knowledge) are perfectly valid, compatible 32 bit x86 CPUs" You're currently correct. Intel have published an outline of a simplified x86 processor that leaves out 16-bit mode and parts of 32-bit, but have not shipped any AFAIK. Apr 6 at 14:29
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    @tpimh You are asking for an opinion of which processor may be best; this is a subjective question with possibly no definitive answer. Rather, it would be better to ask, for example, what was the latest and most powerful consumer 32-bit processor generally available prior to the mainstream introduction of 64-bit processors. As user3528438 mentioned, the Intel Core Duo might be one of the latest (I have a 2006 one) but probably not the fastest or most powerful. Apr 6 at 19:17
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    @tpimh Performance is not objective as benchmarks are always task specific, and with everyone having different tasks it's subjective which is best. Likewise, if you ask for a gaming rig, excluding the best CPUs of the time just because they have instructions isn't anything someone would have done in at the time 64 bit was seen as gimmick,the CPU was bough for itsspeed enhancement. Setting a cut off time would be way more useful than random exclusion of technology. Even more important: 32 Bit x86 is in no way retro by itself. It's just (ifatt all) older, but not retro.
    – Raffzahn
    Apr 6 at 20:26
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    You're the asker, you've got to pick a benchmark you're interested in.
    – knol
    Apr 7 at 7:54

2 Answers 2


Likely the 80376. None of the CPUs you list are "32-bit only" because they also support execution of 16-bit code.

  • 2
    Nice one, you got my upvote. If there is not going to be any other answer, I will accept this one, because technically it's correct by definition, although completely useless to me.
    – tpimh
    Apr 10 at 6:19

You're likely to get a lot of debate on this:

Athlon XPs had a tendency for better performance per clock than a Pentium 4 (really everything here does), especially if something wasn't making heavy use of Intel-only vector instructions.

Pentium 4s reached massive clock-speeds at massive power consumption at the end. They are probably the worst option here, but well supported.

Athlon 64s don't technically meet the requirement but would commonly be run with 32-bit OS's at first: it took a while for 64-bit Windows to become standard. These would probably be faster than anything else in the era.

Core 1 was based on the Pentium M mobile architecture, adapted for desktop, and competed much better with Athlon XPs and Athlon 64s for reasonably efficient performance.

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