H3nrik V! wrote on 2025-09-22, 09:02:

shevalier wrote on 2025-09-22, 05:21:

It doesn't matter what kind of VRM controller it has. There's a sort of "magic relay circuit" between it and the processor, cont […]
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It doesn't matter what kind of VRM controller it has.
There's a sort of "magic relay circuit" between it and the processor, controlled by software.
Considering that dynamic voltage regulation only appeared in Tualatin mobile CPU, for descktop Mendos/Katmai/Cooper/Tualatin it's handled by SOME vendor-specific solution.
And if Abit hadn't included the CooperMine detection feature in the version 1.0 motherboard, it "magic relay" wouldn't have enabled or switched.
If this "software control" hadn't existed, and the VID signals were transmitted directly, everything would have worked.
However, version 1.01 may differ from 1.0 by a single bootstrap resistor, which sets a different initial value for one of the VIDs.
For example, with "11111" - no CPU (or 1.2V for this PWM controller from On-semi) to something else.

Don't get hung up on "starting at 1.3V" and "which PWM controller is used."
This is a "black box" that behaves exactly as it does, and there is no other behavior.

I get your point, but it's a hard fact that some motherboards do have VRMs, that doesn't support lower than e.g. 2.0Volts. My own Intel SE440BX-2 in early revision is an example. But agreed, it will only work if the "black box" is wired correctly. But then again, if BIOS allows selecting 1.3 Volts, I'd suspect that the board is wired to be able to do that.

Yes and no. It can accept the command from the smi channel to change to <1.8v, but the spec at the time for autodetection was probably only down to 1.8v.
It all depends on whether the bh6 was designed around the Pentium 2,or 3.

Iirc the spec was vrm 8,8.1,8.2,and 8.3.
Pentium pro, 2,3, tualatin. The penultimate full full spec to support them all was 1.3-3.5v, but most vrms were a subset targeting an era.

myne wrote on 2025-09-22, 13:54:

Yes and no. It can accept the command from the smi channel to change to <1.8v, but the spec at the time for autodetection was pr […]
Show full quote

H3nrik V! wrote on 2025-09-22, 09:02:

shevalier wrote on 2025-09-22, 05:21:

It doesn't matter what kind of VRM controller it has. There's a sort of "magic relay circuit" between it and the processor, cont […]
Show full quote

It doesn't matter what kind of VRM controller it has.
There's a sort of "magic relay circuit" between it and the processor, controlled by software.
Considering that dynamic voltage regulation only appeared in Tualatin mobile CPU, for descktop Mendos/Katmai/Cooper/Tualatin it's handled by SOME vendor-specific solution.
And if Abit hadn't included the CooperMine detection feature in the version 1.0 motherboard, it "magic relay" wouldn't have enabled or switched.
If this "software control" hadn't existed, and the VID signals were transmitted directly, everything would have worked.
However, version 1.01 may differ from 1.0 by a single bootstrap resistor, which sets a different initial value for one of the VIDs.
For example, with "11111" - no CPU (or 1.2V for this PWM controller from On-semi) to something else.

Don't get hung up on "starting at 1.3V" and "which PWM controller is used."
This is a "black box" that behaves exactly as it does, and there is no other behavior.

I get your point, but it's a hard fact that some motherboards do have VRMs, that doesn't support lower than e.g. 2.0Volts. My own Intel SE440BX-2 in early revision is an example. But agreed, it will only work if the "black box" is wired correctly. But then again, if BIOS allows selecting 1.3 Volts, I'd suspect that the board is wired to be able to do that.

Yes and no. It can accept the command from the smi channel to change to <1.8v, but the spec at the time for autodetection was probably only down to 1.8v.
It all depends on whether the bh6 was designed around the Pentium 2,or 3.

Iirc the spec was vrm 8,8.1,8.2,and 8.3.
Pentium pro, 2,3, tualatin. The penultimate full full spec to support them all was 1.3-3.5v, but most vrms were a subset targeting an era.

By the way, according to Retroweb, the Intel SE440BX-2 is perfectly capable of delivering 1.3 V. Because it has an SC1185 controller.
Intel engineers simply decided to force the VID4 to be pull-up.
On the other hand, this is Intel.
Its BIOS won't let an unsupported processor boot anyway.
And no one has figured out how to patch them.

I ordered a different Coppermine Slot 1 to test, it’ll be here at the end of the week. If that one doesn’t work then it’s a mobo problem.

My next question is: are the Rev. 1.1 BH6 boards Coppermine-compatible? I’ve seen some mention that the 1.1 revision was done because the voltage reqs were lowered for the Coppermines after the BH6 already came to market, so theoretically they should detect one more reliably than a 1.0 board, right?

myne wrote on 2025-09-22, 13:54:

Yes and no. It can accept the command from the smi channel to change to <1.8v, but the spec at the time for autodetection was pr […]
Show full quote

Yes and no. It can accept the command from the smi channel to change to <1.8v, but the spec at the time for autodetection was probably only down to 1.8v.
It all depends on whether the bh6 was designed around the Pentium 2,or 3.

Iirc the spec was vrm 8,8.1,8.2,and 8.3.
Pentium pro, 2,3, tualatin. The penultimate full full spec to support them all was 1.3-3.5v, but most vrms were a subset targeting an era.

Pretty sure P3 wasn't there when the BH6 released 😀 Well, at least, here in Denmark we hadn't heard of it 🤣