AMD 486DX4 100MHz

[Zacko10000]

I have an AMD 486DX4 100MHz processor and was wondering, will this work on any old socket 3 486 motherboard? The original motherboard was experiencing RAM problems and I fear the RAM slots may be damaged. I've got more 486 66 and 33 MHz chips with their motherboards. Can I put the chip on one of these and just manipulate the jumper settings? Do most of these boards even support the DX4 chips? Being an AMD rather then Intel, can I overclock it at all?
Thanks

[CMonster]

No, sorry, the chip will not achieve the 100mhz on just any old 486 motherboard ..the board has to support the chip and it's multiplier...but

I have heard stories of some DX4 100s that also work on a 2x multiplier and some people have reported setting the bus speed to 50mhz for 2x50=100 (but this is almost impossible to achieve due to the 50mhz bus overclocking peripherals beyond tolerance) - while others have attested to speeds of 80mhz (2x40) and 120mhz using 3X40mhz- the possibilities are definately there, but as always it depends on the board.

[GIMOER]

I have an AMD 133 and have run it on 6 diffrent mboards.Including an old packard bell and half did not even require moving any jumpers at all.This was to get it to 100mhz though not 133 since very few supported the 133AMD.But I would try the boards but be careful of cpu voltage as most 100DX4s are not 5volt processors.

[OuTpaTienT]

Yes is probably will work. The multiplier in in the chip on 486's (and cannot be changed). The motherboard doesn't even have any idea what a CPU multiplier is.

If you got a few of them, then find a 486 m/b that will run at 40mhz (as opposed to the typical 33mhz). That DX4 on a 40mhz bus will give ya a CPU of 120mhz. This is an almost guaranteed overclock on any DX4 (AMD or Intel).

[CMonster]

sorry to tell you this again, but if you put a DX2 -66 or a DX4 -100 on a board that is built for a DX -33 and no higher, the chips will all run at a maximum of 33mhz (1x the bus speed) UNLESS it is an overdrive type chip as some of the AMD -133mhz variety are...in that case the multiplier is indeed built into the chip.

[This message has been edited by CMonster (edited 07-07-99).]

[Zacko10000]

Thanks, I think I found another board that might support it, all I need to do is move a few jumpers. Unfortunatly I would lose my PCI slots http://www.sysopt.com/forum/frown.gif

[OuTpaTienT]

Hope ya get things working Zacko.

And CMonster, no offense, but I just don't know where you're coming from. I've owned 5 different DX2's (3 overdrives, 2 plain DX2, all Intel) and I've owned 3 DX4's (2 AMDs, 1 Intel) plus I've built/worked on many more times that. I've never seen a DX2/4 that didn't have the multiplier in the chip.

As a matter of fact, I specifically remember my very first DX2/66 Intel chip. I remember it because it cost over $500 just for the CPU. I used it to replace my DX/33 on it's 33mhz m/b. (and when that m/b was made, the DX2 wasn't even a spark in some engineer's brain yet). Out goes the old DX/33 and in goes the new DX2/66 (in the 33mhz max m/b) and BAM, 66mhz. And this was one of the very early (and still expensive) DX2's.

So, a 486 that runs faster than the bus speed and doesn't have the multiplier on the chip, just doesn't exist. If you know otherwise, please fill me in.

[CMonster]

I stand corrected: I believe you:

I will be the first to say that my 486 experience is limited to 5 boards and only 1/2 dozen or so chips - most of them DX-33s, only one Intel DX2 and a Cyrix DX2. I have a good Intel DX2-66 chip and a standard Biostar VLB board that came with a 486DX-33 chip on it, I put the 486DX2 on it and BAM -it ran at only 33mhz...BUT when I put the 486DX2 chip in another board (a board that has specific different jumper settings printed on the board for the Intel DX, and DX2, and again separate settings for AMD and Cyrix chips), then it ran at 66mhz...Sorry that I do not have an explanation for this... http://www.sysopt.com/forum/wink.gifI guess we get different chips here in California http://www.sysopt.com/forum/smile.gif

I just gave a 3rd different, generic, 486 board to, my neighbor, because it did not have jumpersettings for anything other than an Intel DX chip - I never even tried my DX-2 chip in the board because of the disappointing rresults on the previous attempts - my neighbor did try one of his DX-2s in the board and said that it ran at only 33mhz - I took his word for it. I do not have any 486 chips running in my house at this time....but a few keychains.

Thanks for the tip, I will experiment again the next time I get the chance.

[This message has been edited by CMonster (edited 07-08-99).]

[OuTpaTienT]

Well, it seems I stand corrected also then. I mean, you've obviously run into issues I haven't. Which really should be no surprise casue I'm sure you know, as well as I do, the WIDE variety of hardware vendors and their compatability issues (especially back in the 486 days).

Just FYI, wasn't trying to pick a fight or anything, just relaying my experience, as were you.

BTW, that "California thing" doesn't fly, because I'm here too. http://www.sysopt.com/forum/wink.gif

...ya know, I wonder if it had anything to do with different voltages for the CPUs? It's hard to say cause that whole 'overdrive' thing was kinda a scam anyways. Remember some m/b had a specific overdrive socket and if you upgraded to an overdrive cpu, you were supposed to put it in the overdrive socket and KEEP your existing cpu in it's place (even though it would be disabled). It was such an obvious scam because if you didn't have an overdrive socket you could just remove your cpu and put the overdrive in for the exact same effect. Geeeez! Plus SX & DX & SLC variatons on the same cpu, I'm glad those days are over.

[This message has been edited by OuTpaTienT (edited 07-08-99).]

[CMonster]

OuTpaTienT - fighting? actually I am grateful to you for teaching me something I truely didn't know...I am compulsive at assumptions and I just hate to get caught with my foot in my mouth (where it is more often than not). I really need to stop drawing blanket conclusions from one or two isolated experiences.

I have been basically throwing out 486 motherboards because I assumed that none of them could support the DX2s (which I can get for $9.95)...I may try to salvage a few of them for donation computers.

Speaking of donations:

If you live in Sothern California, there are of course many worthy charities, but this is my favorite, because 27years ago I used to live there:

Pacific Lodge Boy's Home, 4900 Serrania Avenue, Woodland Hills, CA 91364

Phone: 818-347-1577

Please donate any old working systems or monitors.

You will never know how much good it will do.

[OuTpaTienT]

http://www.sysopt.com/forum/smile.gif Sorry, I'm in Northern California. Hmmm, but really I guess I should be sorry for you, cause you're in 'Southern' California. (hehe, that's just a little CA in-state humor.)

I've have given a few systems to my neighborhood school. And if not there then I'm giving 'em away to people I know. Only qualifications I demand are that they are interested and want to learn about (or with) the computer, or that they have a small child. If the have a young kid, I just KNOW FOR A FACT the system will get used and the world will have one more computer geek. http://www.sysopt.com/forum/smile.gif

On second thought, is this really a good thing I'm doing??? http://www.sysopt.com/forum/wink.gif

[CMonster]

..not intending to hijack the thread any further:

errr..Nothern California - I'm jealous! http://www.sysopt.com/forum/wink.gif

[800XL]

Intel DX/2 chips: Run at 2x multiplier no matter what. There is no way to change it. Most AMD and Cyrix chips are this way as well. All Intel DX2's run at 5 volts, Cyrix and AMD are mixed 3.3v and 5v. They should say which on top.

Intel DX4: Has one pin for multiplier settings. Can be run at 3x or 2x. Cyrix and AMD run the same. Overdrive Intel DX4s can run on 5 volts, but only because they have a voltage regulator. All others run at 3.3v.

Cyrix and AMD 586: Some Cyrix chips were 2x/3x and some(**** few) were 3x/4x. All AMD 5x86 that I know of were 3x/4x. The 4x setting is the same as the 2x setting for DX4s. Both AMD and Cyrix were 3.3v with a few of the Cyrix chips being able to tolerate 5 volts. Not exactly consistant, but they would do it sometimes.


To answer Zacko's original question, if you can get 3.3 volts set on that motherboard, it is worth a shot. Don't believe what the bios says for CPU speed though, run some program to check it.