set the multiplier to 2x, the chip should interpret that as 6x. They were built that way to tackle the problem of multiplier limitations.

Of course, that would mean 600 MHz with 100 FSB, so it might not run stable - reduce to 75 MHz FSB for 450 MHz or something in between, if available.
Or try increasing the core voltage, at your own risk.

In any case you should try to get a real manual for the motherboard, if at all obtainable. Some Compaq enthusiasts here will help you out.

There actually is a method to set the multiplier via software for K6-2+ and K6-III+ chips, called setmul.
SetMul - Multiplier control for VIA C3 / AMD K6+7+8 Mobile / Cyrix 5x86
Those chips are just not quite as easy to download 😉

533 is 97 x 5.5, so set the fsb to 97 and multiplier to (I think) 1.5 (for 5.5)

Unfortunately, the manual only has jumper settings listed for 3x, 3.5x, and 4x. Does setmul only work on 'plus' model CPUs? Thank you for your responses. Here is the information that I have at hand from a PDF manual:

Have you tried undocumented jumper combinations for the multiplier? Some should work.

Hopefully someone who knows the chipset can tell you more for certain.

From the table we can extrapolate that J14=BF1 and that 1-2=BF signal high (corresponding jumper open on most motherboards) /2-3=BF signal low (corresponding jumper closed on most motherboards).
As soon as we know all three BF jumpers we can set any multiplier supported by the K6-2.
To figure out the other two BF jumpers please set the jumpers as follows:
Multiplier: J14 2-3 / J15 2-3 / J16 1-2.
FSB: J8 2-3 / J9 2-3 / J10 1-2 / J11 1-2 / J12 1-2. (100MHz)
If it posts at 250MHz we know J15=BF0 and J16=BF2.
If it posts at 500MHz we know J16=BF0 and J15=BF2.
If it does something else my conclusions are probably wrong. 😄

Cuttoon wrote on 2022-03-12, 01:46:

set the multiplier to 2x, the chip should interpret that as 6x. They were built that way to tackle the problem of multiplier lim […]
Show full quote

set the multiplier to 2x, the chip should interpret that as 6x. They were built that way to tackle the problem of multiplier limitations.

Of course, that would mean 600 MHz with 100 FSB, so it might not run stable - reduce to 75 MHz FSB for 450 MHz or something in between, if available.
Or try increasing the core voltage, at your own risk.

In any case you should try to get a real manual for the motherboard, if at all obtainable. Some Compaq enthusiasts here will help you out.

There actually is a method to set the multiplier via software for K6-2+ and K6-III+ chips, called setmul.
SetMul - Multiplier control for VIA C3 / AMD K6+7+8 Mobile / Cyrix 5x86
Those chips are just not quite as easy to download 😉

A k62 isn’t going to be happy at 6x 100fsb.

Question to OP

We need a good pic of your motherboard can you pull it and take a front and back pic?

https://www.ultimateretro.net/en/
Or find it here (but be sure it’s exactly the same because if you are wrong out help will be misguided.)

Basically I’ve seen many threads like this and it’s all hopeless without starting with a good awareness of EXACTLY the mobo we are helping with.

I’m gonna make a guess here:

J14 appears to be Bf1

2-3 is on 1-2 is off

5.5x is either

J14off j15off j16 on
J14off j15 on j16 off

Typically there is no harm in trying combinations of 1-2 or 2-3 just don’t do 1-1 or 1-3 or anything weird like that.

Edit, I see someone else beat me to it, looks like I should finish reading the thread before replying 🤣. Though I concluded 2-3 as on/closed

In any case looks like we both suggested the same two settings to try.

Another thing, but maybe something for later, you can probably get a k6-3+ running in this at 600 mhz which will be a significant improvement over even the k6-2 533 with its l2 cache that the + cpus bring

See my signature about 2+ To 3+ Mod

Which brings us back around to your OP question

These + cpus do actually support software multiplier switching from windows.

TOMMY_THE_DOG wrote on 2022-03-12, 02:40:

Does setmul only work on 'plus' model CPUs?

Correct. You need a + model of K6/2 in order to change multipliers using setmul.

However, the K6/2 CPU will support motherboard jumper settings that are not documented in the motherboard manual, in order to achieve the CPU Mhz you want. It is a common setup scenario faced when dealing with K6/2 systems.

Sphere478 wrote on 2022-03-12, 07:06:

Though I concluded 2-3 as on/closed

I did as well. A closed BF jumper usually means the signal gets pulled low by the motherboard. That's why a closed BF jumper ('on' as in 'jumper on pins') gives a logical signal of 0 while leaving the jumper off will result in a logical 1 on K6 CPUs because of internal pullups. Jumper 'on' means signal 'off'. It's very counterintuitive.😄

Doornkaat wrote on 2022-03-12, 08:23:

Sphere478 wrote on 2022-03-12, 07:06:

Though I concluded 2-3 as on/closed

I did as well. A closed BF jumper usually means the signal gets pulled low by the motherboard. That's why a closed BF jumper ('on' as in 'jumper on pins') gives a logical signal of 0 while leaving the jumper off will result in a logical 1 on K6 CPUs because of internal pullups. Jumper 'on' means signal 'off'. It's very counterintuitive.😄

🤯 🤣

Makes sense actually. Thx for the clarification.

Sphere478 wrote on 2022-03-12, 09:03:

Doornkaat wrote on 2022-03-12, 08:23:

Sphere478 wrote on 2022-03-12, 07:06:

Though I concluded 2-3 as on/closed

I did as well. A closed BF jumper usually means the signal gets pulled low by the motherboard. That's why a closed BF jumper ('on' as in 'jumper on pins') gives a logical signal of 0 while leaving the jumper off will result in a logical 1 on K6 CPUs because of internal pullups. Jumper 'on' means signal 'off'. It's very counterintuitive.😄

🤯 🤣

Makes sense actually. Thx for the clarification.

I have this table with multiplier settings for various S7 CPUs that operates with 1 (signal high/no jumper) and 0 (signal low/jumper set) and it every time I use it it takes me a minute to wrap my head around it again.😂

Doornkaat wrote on 2022-03-12, 06:22:

From the table we can extrapolate that J14=BF1 and that 1-2=BF signal high (corresponding jumper open on most motherboards) /2-3 […]
Show full quote

From the table we can extrapolate that J14=BF1 and that 1-2=BF signal high (corresponding jumper open on most motherboards) /2-3=BF signal low (corresponding jumper closed on most motherboards).
As soon as we know all three BF jumpers we can set any multiplier supported by the K6-2.
To figure out the other two BF jumpers please set the jumpers as follows:
Multiplier: J14 2-3 / J15 2-3 / J16 1-2.
FSB: J8 2-3 / J9 2-3 / J10 1-2 / J11 1-2 / J12 1-2. (100MHz)
If it posts at 250MHz we know J15=BF0 and J16=BF2.
If it posts at 500MHz we know J16=BF0 and J15=BF2.
If it does something else my conclusions are probably wrong. 😄

That got it to 550MHz! Woohoo! Mission accomplished! Thank you so much everyone.
I got this CPU for $12, so it is a good upgrade! I know that the plus models are a bit better, but for a system with no AGP slot, I don't think the upgrade would be worth it for me in this machine. Thank you again.

I imagine that a CPU nominally rated at 533MHz will be fine at 550. My FSB is still at 100MHz.

Congrats! 😃👍
Will you let us know what jumper config got you to 550MHz?

Oh man, Redneck Rampage just posted a Dos4GW error and crashed. That's never happened before. Jazz Jackrabbit is giving the runtime 200 error. Is there anything wrong with just patching it like I did for my Coppermine machine? The game worked fine at 400MHz on the K6-2. Maybe I will pick up a 2+ eventually for that software multiplier. It would be nice to be able to bring the system down for compatibility. It's not in the budget right now, though.

All that said, Duke Nukem 3D is performing like a champ, and it is a better game than RR anyway. I just like RR as a benchmark.

Doornkaat wrote on 2022-03-12, 16:56:

Congrats! 😃👍
Will you let us know what jumper config got you to 550MHz?

The one that you thought would take it to 500MHz:

Multiplier: J14 2-3 / J15 2-3 / J16 1-2.
FSB: J8 2-3 / J9 2-3 / J10 1-2 / J11 1-2 / J12 1-2. (100MHz)

Huh, that either contradicts the manual or there's stuff going on that I don't know about.
I had been wondering why they would put the jumpers in another order than BF0, BF1, BF2. Seems like that's the order they're in after all.👌

TOMMY_THE_DOG wrote on 2022-03-12, 16:49:

That got it to 550MHz! Woohoo! Mission accomplished! Thank you so much everyone. I got this CPU for $12, so it is a good upgr […]
Show full quote

Doornkaat wrote on 2022-03-12, 06:22:

From the table we can extrapolate that J14=BF1 and that 1-2=BF signal high (corresponding jumper open on most motherboards) /2-3 […]
Show full quote

From the table we can extrapolate that J14=BF1 and that 1-2=BF signal high (corresponding jumper open on most motherboards) /2-3=BF signal low (corresponding jumper closed on most motherboards).
As soon as we know all three BF jumpers we can set any multiplier supported by the K6-2.
To figure out the other two BF jumpers please set the jumpers as follows:
Multiplier: J14 2-3 / J15 2-3 / J16 1-2.
FSB: J8 2-3 / J9 2-3 / J10 1-2 / J11 1-2 / J12 1-2. (100MHz)
If it posts at 250MHz we know J15=BF0 and J16=BF2.
If it posts at 500MHz we know J16=BF0 and J15=BF2.
If it does something else my conclusions are probably wrong. 😄

That got it to 550MHz! Woohoo! Mission accomplished! Thank you so much everyone.
I got this CPU for $12, so it is a good upgrade! I know that the plus models are a bit better, but for a system with no AGP slot, I don't think the upgrade would be worth it for me in this machine. Thank you again.

I imagine that a CPU nominally rated at 533MHz will be fine at 550. My FSB is still at 100MHz.

What cpu is it? What are the letters of the model? Example “k6-2+ 570acz”

Yeah, 550 is probably fine for a 533

Do stability testing to confirm it’s stable, may need a 0.1v bump

Speaking of, you should check your voltage

A resistor leg in the middle pin on the notched corner side of the cpu to ground with a volt meter is the easiest way to test. Close the lever.

Btw, what setting did you use? What mobo is it? We could document it on ultimate retro if you can provide more infos

Edit: reading further,
Try the next fsb setting (95mhz if you have it) but before you do that, confirm voltage the 550 uses .1v more than the 533

TOMMY_THE_DOG wrote on 2022-03-12, 16:59:

Oh man, Redneck Rampage just posted a Dos4GW error and crashed. That's never happened before. Jazz Jackrabbit is giving the runtime 200 error. Is there anything wrong with just patching it like I did for my Coppermine machine? The game worked fine at 400MHz on the K6-2. Maybe I will pick up a 2+ eventually for that software multiplier. It would be nice to be able to bring the system down for compatibility. It's not in the budget right now, though.

Setting up physical switches is another option; it's what I did for my K6/2. So you can flick a couple of switches before turning on, to set various speeds between 166 and 500Mhz. Then on top of that, setmul can be used to disable L1 cache. Overall it covers quite a range.