Gonzo, I am curious about your Quake II result at 180 MHz. I thought 16.5 fps sounded a tad high, so I ran some tests on my Am5x86-180 system (m919) with a Voodoo2 card (800x600x65K) and acquired the following:

DOOM = 75.22 fps
Quake DOS = 21.1 fps
GLQuake = 29.8 fps
Quake II (GL) = 11.4 fps

By way of comparison, you reported the these with a GeForce2:

DOOM = 61.4 fps
Quake DOS = 18.8 fps
GLQuake = 27.5 fps
Quake II (GL) = 16.5 fps

The outlier is the Quake II score. Is the GF2 so much more optimised for Quake II than on a Voodoo2? I was able to dig up some of charts of mine from 2014 here: Re: Modern graphics on a 486

I ran an Am5x86 at 160 MHz with 640x480x65K using a GF2MX400, whereby Quake II scored 15.5 fps. With a POD100, Quake II scored 17.5 fps. Unfortunately, I do not have the Voodoo scores to compare against the GF2 on the same system. However, I noted a Cyrix 5x86-133w/Voodoo3, yielded 11.1 fps in Quake II.

Now, looking at the GLQuake chart with an Am5x86-160, the Voodoo3 should have a slight edge over the GF2, but maybe Quake II just runs that much faster with a GeForce2?

feipoa wrote on 2024-06-16, 11:18:

Gonzo, I am curious about your Quake II result at 180 MHz. I thought 16.5 fps sounded a tad high....maybe Quake II just runs that much faster with a GeForce2?

Yes, feipoa, the result is correct (I confirm this), all the pictures from the previous site are authentical. This was the reason for me to ask pshipkov (as well you, and all the other users here) about other Quake II results here in the forum.
So I have decided to use the GF2MX-400 together with detonator 12.41 (having GLQuake + Quake II and the same time, but no 3DMARK 99MAX) instead of e.g. detonator 44.04 (having 3DMARK but no OpenGL) .
Using 512 KB (HOT-433 rev.4) instead of 1024 KB L2 (HOT-433 rev. 1) with timings 3-2-3 @ 180 MHz/FSB 60 reduces the result of about 0,3 FPS.

For the Voodoo 2/3, there is OpenGL and Direct3D possible at once using the same driver.

feipoa wrote on 2024-06-16, 10:30:

gonzo, I think pshipkov is referring to using a cheap buck regulator, like that shown here: Re: Custom interposer module for TI486SXL2-66 PGA168 to PGA132 - HELP! , to run the CPU off the 12 V power supply, then have the voltage stepped-down using the buck regulator. You can see what I did in the above link to run my SXL2 at 5.25 V instead of 5.0 V.

In short, you will want to find an unused PGA-168 socket. Cut off all the pins on that socket which correspond to the incoming voltage (Vcc) from the motherboard. There will be about 23 pins. You are cutting them off so that you no longer power your CPU from the motherboard's CPU voltage regulator. Instead, you are powering it from the 12V line via the switching (buck) regulator. Connect the input of your switching regulator to the 12 V rail on the PSU (via molex), then connect the output of your switching regulator to the cut-off Vcc pins on your PGA-168 socket. Use the trim pot on your switching regulator module to adjust the voltage, anywhere from about 3 V to 11 V. I'd suggest setting it for 5 V to start. If you need greater precision, you could install one of those blue Bourns trimmers like I show in the above link. Sometimes the trim pots that come on these cheap buck regulators don't work well at all. Mine was faulty.

Thank you, feipoa, I see, this will take some time to be done. Not sure I have this time in the next weeks, but will see how far I can go.

That is interesting. From my previous testing in the aforementioned thread:

feipoa wrote on 2012-11-10, 02:45:

PNY GeForce2 MX400 64MB
Win95c
NVIDIA Detonator v12.41 for Am5x86, however I was unable to get Direct3D working (e.g. Outlaws, MDK). OpenGL works with the Am5x86 with v12.41, however Direct3D games will require a POD. NVIDIA Detonator v77.72 for POD.

But it looks like you found an Detonator driver (v44.04) that actually works with D3D and an Am5x86. Is this the only version which let D3D function with an Am5x86, albiet without OpenGL support?

feipoa wrote on 2024-06-16, 12:14:

But it looks like you found an Detonator driver (v44.04) that actually works with D3D and an Am5x86. Is this the only version which let D3D function with an Am5x86, albiet without OpenGL support?

You can see my original posting here Re: Modern graphics on a 486

I just did a quick test with the HOT-433 rev. 1 and 256 KB L2 (3-2-3) at 180 MHz.
Quake II seems to take an advantage from more L2 cache installed - the results are in this case the lowest one (15,8 FPS).

Does anybody have an idea, how the FSB of the HOT-433 rev. 1 can be changed to have frequencies between 50 and 66 MHz (except of 60), or faster than 66 MHz?

To reach CPU-frequencies between 180 and 200, or above 200 (but less than 240 MHz).

Without this information, it has no sence to increase the CPU-voltage over 5 Volt, as shown by feipoa and pshipkov above.

Thank you.

H3nrik V! wrote on 2024-06-16, 10:49:

You should never try to regulate a voltage with resistors alone, it will vary with current few m draw, so in idle you might be looking at close to 12V on the supply, if you run to 5.xx under full load

Correct. I was too short in my reply.
Feipoa provided the correct answer.
Here is a good summary on the subject. Check the first reply.
https://electronics.stackexchange.com/questio … -with-resistors

—-

hot433 v1 has clockgen that does 60/66/83, it also has 3 jumpers, so it is matter of 1 minute checking which of the 9 possible jumper configs gets you 66.
It is either middle jumper short, or the two outward ones short.

pshipkov wrote on 2024-06-16, 17:12:

hot433 v1 has clockgen that does 60/66/83, it also has 3 jumpers, so it is matter of 1 minute checking which of the 9 possible jumper configs gets you 66

This was not the question:)
The jumper-positions for 66 MHz are already known, showed by feipoa some time ago somewhere here in the forum (JP1: 1-2 / JP2: 2-3 / JP3: 1-2)

The interesting things are:
- for a CPU-frequency slightly above 200 MHz: to reach FSBs slightly above 66 MHz (83 will be too high), or slightly above 50 MHz (but less than 60 MHz)
- for a CPU-frequency over 180 MHz but less than 200 MHz: to reach FSBs more than 60 MHz but less than 66 MHz
Maybe another clock-generator should be used, or some additional manipulations on the existing clock-generator have to be done.
As I am not very familiar with electrical details for some components, help from more experienced people is necessary.

Also another question is how to reach a CPU-voltage more than 4,0 Volt, but less than 5,0 Volt.

feipoa wrote on 2024-06-16, 10:30:

Use the trim pot on your switching regulator module to adjust the voltage, anywhere from about 3 V to 11 V. I'd suggest setting it for 5 V to start

feipoa, this should answer my question about how to reach CPU-voltages over 4 V, but less than 5 Volt.
Sorry, I apparently did not read this part of your posting more careful...Thank you once again.

feipoa wrote on 2024-06-16, 10:30:

In short, you will want to find an unused PGA-168 socket. Cut off all the pins on that socket which correspond to the incoming voltage (Vcc) from the motherboard

Am I right to use a desoldered used socket, too...? 😀

Of course.

feipoa wrote on 2024-06-16, 10:30:

You can see what I did in the above link to run my SXL2 at 5.25 V instead of 5.0 V.
...you are powering it from the 12V line via the switching (buck) regulator.

Another question: how many Ampere should the buck-regulator offer? There is a wide range on ebay from about 1,5 A to 5 A

Maximum values for Am5x86: ~5V, ~1A, ~4W.
Looks like ~1.5A buck-regulator will be fine.

pshipkov wrote on 2024-06-18, 16:06:

Maximum values for Am5x86: ~5V, ~1A, ~4W.
Looks like ~1.5A buck-regulator will be fine.

Thank you, pshipkov.
I am a little bit disappointed with the long time for delivery from China, so I had a look at this one buck-regulator offered from a German-trader:
https://www.conrad.de/de/p/az-delivery-lm2596 … ductDescription

Input-voltage: 4 to 40 V
Output-Voltage: 3,3 to 24 V
Output-Amperage: 2 A constant
Very comfortable because of a display for the Output-Voltage 😀
Price per piece: about 6 Euro

Would this be a good choice?

By the way: how must be the negative pole (ground) of the buck-regulator connected to the PGA-168-interposer? I assume, all the Vcc-pins (23-24 pins) are all only the positive pole...

Nice device. Will be ok.
CPUs VCC pins go to vout+.
In/out negative poles of the regulator to ground.

Btw, if the mission is not the journey, but the end objective, then there is shorter path to there.
I mentioned the option of using Peltier element already, will bring it up again.
Also, the approach you are taking to overvolt the CPU will be more laborious than what i am suggesting.
Basically,
buy this: https://www.ebay.com/itm/224101203802
Plug its wires to a PSU molex connector. Red to +5V, black to GND.
Put a Socket7 sized heatsink and fan on the Peltier.
You are ready to roll.

Water condensation will be minimal, so you will be able to test as is.
If satisfied with the outcome, there is an additional step required for long-term stability - isolation of the peltier element from the surrounding environment. This is another 2 minutes exercise.

pshipkov wrote on 2024-06-19, 17:56:

buy this: https://www.ebay.com/itm/224101203802 Plug its wires to a PSU molex connector. Red to +5V, black to GND. Put a Socket7 […]
Show full quote

buy this: https://www.ebay.com/itm/224101203802
Plug its wires to a PSU molex connector. Red to +5V, black to GND.
Put a Socket7 sized heatsink and fan on the Peltier.
You are ready to roll.

Nice thing, really, I will keep it in mind.
My intention is to see how much I can overclock my CPUs here without any Peltier-cooling (as they are really stable at 180 MHz/4V, 180 MHz/5V and 200 MHz/5V with more or less "normal" cooling, as shown above).
No need of using Peltier is for me a really big advantage, so I will keep any Peltier away as good as I can 😉

As the first step, I will see if a stable 180-MHz-CPU can reach exactly 200 MHz at a slightly higher voltage, as it needs for 180 MHz.
As the second step, for reaching CPU-frequencies above 200 MHz, a change of the FSB will be necessary, as shown above - this will need some help from more experienced users here, as I am not very familiar with the electrical part of the relevant components (e.g. clock-generator).

pshipkov wrote on 2024-06-19, 16:42:

Nice device. Will be ok.
CPUs VCC pins go to vout+.
In/out negative poles of the regulator to ground.

So the V(out) negative pole of the buck-regulator does not have any contact with any pin of the interposer? So it goes directly to ground somewhere on the mainboard?

yes

gonzo wrote on 2024-06-19, 18:49:

As the second step, for reaching CPU-frequencies above 200 MHz, a change of the FSB will be necessary, as shown above - this will need some help from more experienced users here, as I am not very familiar with the electrical part of the relevant components (e.g. clock-generator).

You can remove the on-board clock generator and wire a DIP-14 socket for crystal oscillators or clock generators that offer more frequency options.
Didn't try that myself since it is a bit invasive to the integrity of the motherboards.
Can be the next stage for 486 overclocking.

Keep in mind that 180MHz can be achieved with tight BIOS timings on selected motherboards.
For 200MHz wait states have to be relaxed. This will diminish performance.
So tight 180MHz is roughly equal to relaxed 200MHz.

I can get 240MHz with Peltiers blazing at 12V, but was never able to complete POST.
With that said, the flexibility to use crystal oscillators (or other clockgens) with more inbetween frequencies can potentially move the bar further up from where is now - somewhere between 200 and 230 MHz.