VOGONS


First post, by Carlos S. M.

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Recently, i got an old PC with a working Shuttle HOT-637 which is based on the Intel 440LX and have multiple options for multiplier and FSB, but i noticed there are a 50 and 60 MHz option for FSB as well as the usual 66/75/83 mhz options, i also see multiplier options from 2x up to 5x in the board. I wonder if that board is really good for extreme Pentium II underlocking?

Did someone saw another Slot 1 mobo with options for FSB speeds below 66 MHz, do they also work? I haven't tried the FSB speed options in this board yet and i don't have an unlocked Pentium II (afaik) to take advantage with it though

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What is your biggest Pentium 4 Collection?
Socket 423/478 Motherboards with Universal AGP Slot
Socket 478 Motherboards with PCI-E Slots
LGA 775 Motherboards with AGP Slots
Experiences and thoughts with Socket 423 systems

Reply 1 of 15, by Tetrium

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440LX has a better chance at below 66MHz FSB settings. Perhaps you can find more by trying out some of the undocumented jumper settings.
Silkscreened are 5 settings with a possible maximum of 8, so you could go try the other 3 out.

Whats missing in your collections?
My retro rigs (old topic)
Interesting Vogons threads (links to Vogonswiki)
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Reply 2 of 15, by lazibayer

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The PLL-IC seems to be ICS9150F-04 on your board. It's quite blurred so I can't tell it for sure; but if I am correct you can get better 83M settings than the one printed on the board.

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Reply 3 of 15, by Carlos S. M.

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lazibayer wrote:

The PLL-IC seems to be ICS9150F-04 on your board. It's quite blurred so I can't tell it for sure; but if I am correct you can get better 83M settings than the one printed on the board.

The attachment Screen Shot 2017-03-15 at 2.00.17 PM.png is no longer available

it is, the mobo has the ICS9150F-04 PLL-IC. I assume 1-2 would be FS0, 3-4 = FS1 and then, 5-6 = FS2, right?

looks like 0 = ON, 1 = OFF

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What is your biggest Pentium 4 Collection?
Socket 423/478 Motherboards with Universal AGP Slot
Socket 478 Motherboards with PCI-E Slots
LGA 775 Motherboards with AGP Slots
Experiences and thoughts with Socket 423 systems

Reply 4 of 15, by lazibayer

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Carlos S. M. wrote:
lazibayer wrote:

The PLL-IC seems to be ICS9150F-04 on your board. It's quite blurred so I can't tell it for sure; but if I am correct you can get better 83M settings than the one printed on the board.

Screen Shot 2017-03-15 at 2.00.17 PM.png

it is, the mobo has the ICS9150F-04 PLL-IC. I assume 1-2 would be FS0, 3-4 = FS1 and then, 5-6 = FS2, right?

looks like 0 = ON, 1 = OFF

That would be my guess, too

Reply 5 of 15, by sprcorreia

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I have a few Asus that are capable of 50MHz FSB and low multi. I have tested them and they work great underclocking several PII cpus.

Reply 7 of 15, by PhilsComputerLab

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Can you slow down a Slot 1 CPU to the point of speed sensitive games actually working correctly?

I know you can use software slowdowns, but purely done in hardware I'm a bit skeptical that a Slot 1 machine is suitable.

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Reply 8 of 15, by Kamerat

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Carlos S. M. wrote:

Did someone saw another Slot 1 mobo with options for FSB speeds below 66 MHz, do they also work? I haven't tried the FSB speed options in this board yet and i don't have an unlocked Pentium II (afaik) to take advantage with it though

The Abit LX6 can run at 50MHz FSB, but I have to use SetFSB or similar tools as there's no option for it in the BIOS (no jumper settings for FSB).

PhilsComputerLab wrote:

Can you slow down a Slot 1 CPU to the point of speed sensitive games actually working correctly?

I know you can use software slowdowns, but purely done in hardware I'm a bit skeptical that a Slot 1 machine is suitable.

One problem I see with Pentium II CPU's (and P6 CPU's in general) are that they slow down too much when disabeling L1 cache and even the ones with unlocked multiplier aren't flexible enough. clueless1's thread and spreadsheet that you participated in gives you an idea about the flexibility. A VIA C3 Samuel 2 or Ezra(-T) on a slotket might be more useful when it comes to flexibility. I guess my Samuel 2 at 800MHz (12x66MHz) performs like a Pentium II or Celeron at 333-366MHz on my Abit LX6 and slows down to the 386SX 33-40MHz area when running at 175MHz (3,5x50MHz) with L1 cache and branch prediction disabled.

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Reply 9 of 15, by Scraphoarder

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The Dell Optiplex GX1 (BX chipset) comes to my mind with using Ctrl-Alt-\ or Ctrl-Alt-# on the fly to slow it down. I think its no software slowdown, but related to hardware by either disable the cache or clock the cpu down.
Would be strange if there was only Dell who used this feature and maybe this is an undocumented feature from Intel that is possible are on other boards too?

Reply 10 of 15, by Tetrium

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Well, basically it comes down to the hunt of LX boards which have a PLL chip which support lower FSBs, right?
So which PLL chips are we looking for?

Whats missing in your collections?
My retro rigs (old topic)
Interesting Vogons threads (links to Vogonswiki)
Report spammers here!

Reply 11 of 15, by Carlos S. M.

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Tetrium wrote:

Well, basically it comes down to the hunt of LX boards which have a PLL chip which support lower FSBs, right?
So which PLL chips are we looking for?

ICS9150F-04 is one of them, which my Shuttle HOT-637 uses

What is your biggest Pentium 4 Collection?
Socket 423/478 Motherboards with Universal AGP Slot
Socket 478 Motherboards with PCI-E Slots
LGA 775 Motherboards with AGP Slots
Experiences and thoughts with Socket 423 systems

Reply 12 of 15, by gerwin

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Carlos S. M. wrote:

Did someone saw another Slot 1 mobo with options for FSB speeds below 66 MHz, do they also work? I haven't tried the FSB speed options in this board yet and i don't have an unlocked Pentium II (afaik) to take advantage with it though

There was a time when I was actively seeking such motherboards out. It is in this thread 50 to 133MHz FSB on a BX Mainboard with a lot of other things. Usually such boards have the ICS9148xx-26 or ICS9150xx-08 PLL. The older revisions of the well-known Asus P2B are among them. There is also mention of an i815 board that could be persuaded to run at 50MHz FSB.
Some boards support 50MHz FSB as well as any other speed, but IIRC the P2B gets temperamental... oh here it is:

gerwin wrote:

Asus P2B rev 1.04 has a small issue with 50 MHz FSB: it can boot up with 50, or switch to 50 once, but when you change FSB after that it usually hangs.

Still really like the 50MHz FSB support on motherboards. Together with a pre-august '98 Pentium II you can as low as 2.0x50=100MHz. Or you can combine it with a VIA C3 CPU on a slot adapter, like Kamerat already mentioned.
In the past I tested a few dozen old games on system with a downclocked Pentium II/III and there were several problems (often sound related) that went away when going to 200MHz or lower.

Scraphoarder wrote:

The Dell Optiplex GX1 (BX chipset) comes to my mind with using Ctrl-Alt-\ or Ctrl-Alt-# on the fly to slow it down. I think its no software slowdown, but related to hardware by either disable the cache or clock the cpu down.
Would be strange if there was only Dell who used this feature and maybe this is an undocumented feature from Intel that is possible are on other boards too?

Interesting. It would be easy to test if it is L1 cache related. I don't believe Dell really had a way to change the FSB to CPU speed multiplier.

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Reply 13 of 15, by Kamerat

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gerwin wrote:

There was a time when I was actively seeking such motherboards out. It is in this thread 50 to 133MHz FSB on a BX Mainboard with a lot of other things. Usually such boards have the ICS9148xx-26 or ICS9150xx-08 PLL. The older revisions of the well-known Asus P2B are among them. There is also mention of an i815 board that could be persuaded to run at 50MHz FSB.

After reading this I had a look at my Asus P2B-D 1.06 and spotted an ICS 9150AF-08 and the jumper setting for 50MHz on the board.

DOS Sound Blaster compatibility: PCI sound cards vs. PCI chipsets
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Reply 14 of 15, by Kamerat

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The Gigabyte GA-6EM have a clock generator capable of 33MHz FSB, the PLL52C66-05. You might have to modify the board to get access to the lowest clocks.

DOS Sound Blaster compatibility: PCI sound cards vs. PCI chipsets
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Reply 15 of 15, by gerwin

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Kamerat wrote:

You might have to modify the board to get access to the lowest clocks.

Seems like it, as the F3 jumper is not on the motherboard.

--> ISA Soundcard Overview // Doom MBF 2.04 // SetMul