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Thread: Are the 586 architecture based Cyrix MII chips any good? What are your opinions?

  1. #1

    Default Are the 586 architecture based Cyrix MII chips any good? What are your opinions?

    I just bought a system with a questionable CPU choice - A Cyrix M-II 300MHz. I bought the system mainly for the case. It is a fully functioning custom built system with 64MB of ram and a 1MB PCI 2D card and ISA sound card. Windows 98se.

    I remember I once had this same exact Cyrix CPU in a very very late era US manufactured Packard Bell system that I found at the recycle center. A mini tower that still used only simm ram!! Unbelievably behind the times... for a 1999 system... I still have the nice monitor it came with but I sold the tower on Ebay years ago. I didn't really test any games on it.

    I did have another system, a Compaq Presario 5304 with a M-II 366 CPU (last one made before Cyrix bombed out) I remember that system played late 90's games pretty good. But I remember it was the only system where I experienced random graphical glitches while playing a 1996 CD-ROM re-release of Quest for Glory IV: Shadows of darkness. I saw the artifacts while the 3 different characters, the fighter, magic user and thief came out of hiding with the bats in the background right before you choose a character and allocate skill stats.

    I replaced the CPU in that Compaq system with a Pentium Classic 100MHz and 133MHz models and the graphical glitch problems all went away. Funny that.

    These Cyrix CPUs appear to be found mainly in budget brand PC's like this Packard Bell and Compaq, so that makes me think they were nothing special. Cyrix CPUs get a lot of bad rep, but why? What are the reasons?
    Last edited by computerdude92; November 11th, 2019 at 03:55 AM.

  2. #2
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    I would run with it and see what happens. It's not hard to swap out if it is a problem.
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    Cyrix Pentium era CPUs get a bad rap because the early ones (686) ran very hot and while they killed in running Windows apps the FPU was so slow that nobody wanted one for gaming when 3D games were popular (AKA Quake).

    The M2 series ran at 83FSB which only a few SS7 motherboards used and because of the setup ran PCI at 41Mhz not the normal 33Mhz so some cards had issues. So while AMD and Intel were banging out faster and faster chips the Cyrix ones were slow and late to reach market and only used with low cost systems from OEMs.
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    I used to have a box I was given, or found on the road, can't remember. I didn't use it for much, but I felt it worked quite well. I'm sure that helps a lot.

    IIRC it was a 266 M2. I felt kind of attached to it, go figure, maybe because it was free
    Last edited by tipc; November 11th, 2019 at 09:37 PM.

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    It was better than the original line of cache-less Celerons. The 66MHz bus speed versions were good chips for the inexpensive business machine market: stable stodgy and cheap. The higher bus speed variants sacrificed stability for modest performance gains while still trailing both AMD and Intel mid-range chips considerably.

  6. #6

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    The overclocked PCI bus running at 41MHz wouldn't possibly damage the motherboard or the PCI cards attached to it? What kind of problems can happen? Unknown_K mentioned "some cards had issues"

    Why and how did Cyrix 686 chips break apps? Are M-II chips known to do the same? (Other than graphical issues I mentioned in one game)

    I'll replace this CPU with a Pentium MMX 233 when I get my hands on one. I'm going to use this low end system to record MIDI from games and compare different sound cards. I heard some ISA Soundblasters are picky and want an Intel CPU. Is that right?

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    Quote Originally Posted by computerdude92 View Post
    I heard some ISA Soundblasters are picky and want an Intel CPU. Is that right?
    I heard the Soundblaster Live PCI had some issues with AMD VIA chipsets with the 686b Southbridge chips during the Athlon era.
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    Quote Originally Posted by krebizfan View Post
    It was better than the original line of cache-less Celerons. The 66MHz bus speed versions were good chips for the inexpensive business machine market: stable stodgy and cheap. The higher bus speed variants sacrificed stability for modest performance gains while still trailing both AMD and Intel mid-range chips considerably.
    My tweener has a Cyrix M II 300GP 66MHz CPU in it. I put it together five years ago and although I mainly use DOS 7.x I also run ME and Sometimes XP on it. No complaints.
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    The bad rap was very poor FPU performance, which was starting to be a factor in games at the time.

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    I can vouch for the bad FPU performance. I up/sidegraded my first Pentium-socket motherboard from a K5-90 to one of the "166+" 686Ls, and TL;DR:

    * Integer performance was great, it easily felt as zippy with most software as a (non-MMX) Pentium 200.

    * It *sucked hard* running Quake. Might have actually been slower than the K5-90.
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