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Cyrix 5x86 133mhz

Raven

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Edit: It has come to my attention that the Cyrix 133 chips are actually marked 120mhz, because they were intended for 4x20mhz operation - if put into a 33mhz system, 4x33mhz=133mhz, and they work fine that way too.

So if you have a Cyrix 120mhz sitting around that could be what I'm after.

Edit: yeah, I meant 4x, had to swap that.
 
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Anonymous Coward

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I don't think that is exactly the case. *Some* 120MHz and and *some* 100MHz parts have a 4X multiplier instead of the standard 2X multiplier, as there was limited production of chips rated for 4 X 25MHz (100MHz) and even a proprietary 4 x 30MHz (120MHz). Some of these chips *may* work properly at 4x33MHz, but I wouldn't hold my breath on that one. The Cyrix 5x86 chips were notoriously bad overclockers.

There is still hopes for you though. As far as I can recall, almost all the 5x86s rated for 133MHz operation were surface mount parts and sold to a company called "Gainberry" for use in upgrade kits. Be warned that the gainberry chips come in both an AMD and a Cyrix version. I see the 133MHz Cyrix parts pop up on ebay every now and then. They used to be fairly common, but they're becoming more obscure these days.
 

Neon_WA

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here is info on the standard (common) Cyrix parts in both speeds

Cyrix 5x86 120MHz is 3 x 40FSB (3.45V)
Cyrix 5x86 133MHz is 4 x 33FSB (3.6V)

on a side note, the 120MHz chip was given a rating of PR90 (so equivalent to a Pentium 90)

EDIT >> supposedly a 4 x 30FSB (120MHz) was produced but I have not found an evidence on one, but they did make a 4 x 25FSB (100MHz) so it is maybe a 4 x 30 will turn up :)

Double EDIT >> found one :) http://www.pc-atrium.de/html/cyrix5x86.html
 
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Jorg

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The one I have is a Cyrix 5x86-100GP, with factory cooler.

Even at the time that I bought that (I still have the invoice), the -120s were almost impossible to get. (Which is why I have a -100 ;) )
 

Unknown_K

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I have a ceramic Cyrix 5x86-120GP 026-3.6V from 1995, got it from a coworker 11+ years ago when he purchased a P233MMX systemboard from me and was junking his old gear.

All the Cyrix 5x86 chips were hard to find since they came out very late in the 486 era and you needed decent PCI motherboards with the correct cache method and to enable functions to get the most speed from them.

http://www.cpu-world.com/CPUs/5x86/Cyrix-5x86-120GP.html

I never heard of the 133 version, but if the were surface mount only I can see why since I only dealt with removable chips at the time these would have been new. Most people were using Pentiums at that point anyway.

http://web.archive.org/web/19970524022018/www.cyrix.com/process/prodinfo/legacy/5x-mblst.htm Shows boards that support the chip.
 
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Tetrium

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I have a ceramic Cyrix 5x86-120GP 026-3.6V from 1995, got it from a coworker 11+ years ago when he purchased a P233MMX systemboard from me and was junking his old gear.

All the Cyrix 5x86 chips were hard to find since they came out very late in the 486 era and you needed decent PCI motherboards with the correct cache method and to enable functions to get the most speed from them.

http://www.cpu-world.com/CPUs/5x86/Cyrix-5x86-120GP.html

I never heard of the 133 version, but if the were surface mount only I can see why since I only dealt with removable chips at the time these would have been new. Most people were using Pentiums at that point anyway.

http://web.archive.org/web/19970524022018/www.cyrix.com/process/prodinfo/legacy/5x-mblst.htm Shows boards that support the chip.

Dang...that compatibility list is really short!
I got plenty socket 3 PCI boards but only the SP3 is on that list, and that one blew up a couple weeks ago, don't know for sure if it'll work or not (posted topic on vogons about my SP3 board)
 

Raven

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Well that's full compatibility with the chip - even with every advanced feature it has turned off the FPU performance should still best an AMD chip.
 

Unknown_K

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Depends, if the special features are not supported I bet a 486/160 AMD (oc'd 133) would be faster.
 

Raven

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Well yes, but I am thinking from my perspective, in which the system I am working with has a 25/33mhz bus selection, no 40mhz. Thus unless I could make the chip run at 5x33=166mhz I couldn't get one that fast.
 

Jorg

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Dang...that compatibility list is really short!
I got plenty socket 3 PCI boards but only the SP3 is on that list, and that one blew up a couple weeks ago, don't know for sure if it'll work or not (posted topic on vogons about my SP3 board)

Indeed. I have the Biostar MB1433UIV.
 

mainboard777

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Jun 9, 2010
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Intel Overdrive chips
SZ698 ODPR486DX-33
SZ934 DX2ODPR50 v4.0
SZ903 DX2ODP66 V3.0
SZ956 DX4ODP75 V1.1
SZ957 DX4ODP100 V1.1

AMD
AMD-X5-133ADW 3.45 volt (this is a P75)

All of these have the same pin configuration as a standard 486 chip. I have one of each on hand. Is this what you are looking for?

http://www.cpu-collection.de/?l0=co&l1=Intel&l2=i486%20OverDrive This site has excellent pictures, descriptions, multiplies, voltages, etc.
 

ToKi

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Dang... You are 3 years too late. I had a PC with a Cyrix 5x86 133MHz (Yes 133Mhz) that was sitting in my cupboard since 1998 that I tossed. I kept it because it was my first x86 computer. If I knew how rare these processors were I would have kept it.
 

vwestlife

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I dunno if there's anything special about it, but my Cyrix 5x86-120 runs fine when set as 133 MHz (33 x 4), even in a crappy PC Chips "fake cache" VLB/ISA/PCI motherboard.

I think Cyrix never advertised the 133 MHz capability because production quantities of the "120 MHz" 5x86es were so low to begin with, they didn't want to splinter the few available chips between those that should be labelled and priced as "120 MHz" and those that would be "133 MHz" -- nor did they want any overlap, either in price or performance, with the low end of their burgeoning 6x86 series.

Cyrix also had bigger problems to deal with than just speed, in that the Cx5x86 was really a Pentium-class processor shoehorned into a 486 socket, and a lot of older motherboards and BIOSes had problems supporting it correctly. Cyrix compensated for this by intentionally setting some of the Cx5x86's most advanced features to be disabled by default, to help ensure that a less-than-ideal system would have a better chance of being stable. But with a fully supportive motherboard and BIOS, using a software utility to enable these features can achieve a significant performance boost.
 

joekster

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a Cyrix 5x86-120 with a 4x multiplier is rare in itself. I have 3 of the 120mhz 5x86 chips and none of them have the 4x multiplier - 2x or 3x only...
 

feipoa

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Mar 7, 2011
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Canada
A 25 Mhz FSB, 4x Cyrix 5x86 (100 Mhz) might overclock suitably to 133 Mhz with a 33 Mhz FSB. To support this hypothesis, I have run a 5x86-100 at 120 Mhz (40 Mhz FSB) without issue. It performed as my 5x86-120 did in Windows NT 4.0 and Windows98SE with all next generation 6x86 features turned on except for branch prediction.

I have seen some Cyrix 5x86 - 133 chips on eBay in the past, but they slipped away from me. They were not surface mount units. I have read conflicting reports that Cyrix sent their single batch run of this chip to Gainberry, Evergreen, and one other upgrade firm (I forget the name now). I have looked for years on eBay for the correct upgrade unit containing the 133 Mhz version, but have not succeeded in finding it.

I am interested in obtaining a working 4x Cyrix 5x86 if anyone is willing to part with it. I use the 5x86-120 regularly these days (2011).

I have attached two different images of the Cyrix 5x86 133 Mhz. The one with a black background was from an eBay auction about 6 years ago. It slipped away from me because the guy got wind that I was interested, very interested, and he kept upping the price -- it went from $35 to $200 to $600. I never know where it ended up.
 

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