VOGONS


First post, by adalbert

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Is there any possibility of modding such passive slotket (no voltage clamp chip) for Coppermine or Tualatin CPUs on dual CPU Via 694X board? It supports 100 and 133 FSB (Tyan s1834d), but I don't know what would be the I/O voltage there and if such slotket would work at all. In current state I only got some POST codes on diag card, but nothing on screen with overclocked Mendocino CPUs @ 100 fsb (there is no 66 option on M/B). Probably CPU just crashes right away due to overclock and possibly improper voltage. P3 coppermine doesn't work at all with that slotket. Slot 1 CPUs work fine, but i only have some low-end P2 and P3s, better stuff for slot is expensive. I wonder if I would be able to use such slotket with 1GHz P3 or 1.4GHz Tualatins. I remember modding M/B for coppermine cpu long time ago, I wonder if same hack would apply here.

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Repair/electronic stuff videos: https://www.youtube.com/c/adalbertfix

Reply 1 of 10, by maxtherabbit

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Yes I did one such mod. To make coppermine work at all you have to bridge a pair of pins (X4 and AH4, for RESET#) with wire and also remove one of the socket pins (AM2, ground) entirely. Which entails taking the top plastic slide off the s370 and using a vac desoldering gun to evacuate the pin and then lift it out the top.

IMG_20190615_182131.jpg

The one pin that is bridged to the large jumper is connecting slot 1 pin B75 to socket pin X2. This is the second mod required to facilitate SMP with coppermines. It is for the signal BR1# (which on mendocino celerons goes to pin AN15 on the s370.) You need to make sure that B75 (slot1) is connected only to X2 and not also to AN15 (in case your slocket was originally designed to allow for dual mendocinos)

More info on basic cumine mod: http://krick.3feetunder.com/370mod/

Reply 2 of 10, by Oetker

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Coppermine:
You could try the mod maxtherabbit linked - your slotket won't work with Coppermine chips stock.
You have to find out if your VRM chip supports Coppermine and/or Tualatin voltages, but it probably does being that your board offers 133MHz FSB.
As your slotket doesn't have a voltage clamp chip, the CPU will be fed too high a voltage on some pins. I'm not sure how bad that is.

For Tualatin:
A socket mod for Tualatin is also more involved.
You can get Tualatins that include an adapter from eBay, I went with that option as I couldn't easily find a standard Tualatin for sale anyway.
Tualatin CPUs use a lower bus voltage than Coppermine but that doesn't seem to be an issue in practice.

If I were you I'd just get a set of MSI Master slotkets that include the voltage clamp chip and then either go with Coppermines or maybe mod them for Tualatin.

Reply 3 of 10, by adalbert

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maxtherabbit wrote on 2020-08-12, 01:30:

More info on basic cumine mod: http://krick.3feetunder.com/370mod/

Thanks, I will try it. B75 is not connected to anything, but I can solder a thin wire to the top side of gold finger (the contact is on the bottom side).

Oetker wrote on 2020-08-12, 06:07:

You have to find out if your VRM chip supports Coppermine and/or Tualatin voltages

This mobo uses VRM 8.4 standard so it should provide suitable voltage for both.

It even supports Coppermine Slot 1 CPUs out of the box. But I already have some PGA cpus and slotkets so I would like to try to use them. I'm just thinking about that missing voltage clamp. But it supports Slot 1 Coppermines does it mean that the I/O voltage would be OK even without the clamp chip? It has Via 694X chipset and most people seem to be discussing Intel chipsets in such topics.

Repair/electronic stuff videos: https://www.youtube.com/c/adalbertfix

Reply 4 of 10, by Oetker

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adalbert wrote on 2020-08-12, 10:21:

It even supports Coppermine Slot 1 CPUs out of the box. But I already have some PGA cpus and slotkets so I would like to try to use them. I'm just thinking about that missing voltage clamp. But it supports Slot 1 Coppermines does it mean that the I/O voltage would be OK even without the clamp chip? It has Via 694X chipset and most people seem to be discussing Intel chipsets in such topics.

That's a really good question. The specs for the socket 370 Coppermine say

The VCCCMOSpin provides the CMOS voltage for the pull-up resistors required on the system platform. A 2.5 V source must be provided to the VCC2.5pin and a 1.5 V source must be provided to the VCC1.5pin. The source for VCC1.5must be the same as the one supplying VTT. The processor routes the compatible CMOS voltage source (1.5 V or 2.5 V) through the package and out to the VCCCMOS output pin. Processors based on 0.25 micron technology (e.g., the Celeron processor) utilize 2.5 V CMOS buffers. Processors based on 0.18 micron technology (e.g., the PentiumIII processor for the PGA370 socket) utilize 1.5 V CMOS buffers. The signal VCOREDET can be used by hardware on the motherboard to detect which CMOS voltage the processor requires. AVCOREDET connected to VSSwithin the processor indicates a 1.5 V requirement on VCCCMOS. Refer toFigure 5.

So it says .18 micron processors use the lower voltage, and that it can be requested from the motherboard. However that raises more questions:
-Which motherboards support that request signal? Do BX boards, which support 100MHz Slot 1 Coppermines, understand it?
-Does slot 1 have those pins connected to begin with? If so, it could be that on your motherboard everything will work just fine.
-Or do slot 1 Coppermines include their own clamp chip?

Reply 5 of 10, by Oetker

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Datasheet for Slot 1 Pentium 3 says

The voltage clamp logic acts as a voltage translator between the processor’s 1.5 V tolerant CMOS signals and the 2.5 V CMOS voltage on the motherboard. This logic is only available with PentiumIII processors with CPUID=068xh

So Coppermine Slot 1 CPUs include their own clamp. That, and the fact that it this document doesn't talk about requesting a CMOS voltage, leads me to believe that it just isn't supported for Slot 1.
I really would only use your slotket with a Mendocino Celeron.

Reply 6 of 10, by maxtherabbit

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People have been successfully putting slocketed cumines in BX boards for decades without issue. Even the fanciest slockets designed for cumine and/or tualatin don't include level translators. (although they sometimes include VRMs for Vcore)

Reply 7 of 10, by Oetker

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maxtherabbit wrote on 2020-08-12, 13:29:

People have been successfully putting slocketed cumines in BX boards for decades without issue. Even the fanciest slockets designed for cumine and/or tualatin don't include level translators. (although they sometimes include VRMs for Vcore)

For example the MS-6905 V2.x includes a chip to limit the 'CMOS pull-up voltage', this was added for Coppermine support.
The bus voltage (AGTL vs AGTL+) isn't modified, I find conflicting reports on if the Powerleap IP3 does so but anyone using an interposer for Tualatin support will be using the higher voltage.

Reply 8 of 10, by maxtherabbit

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Oetker wrote on 2020-08-12, 13:51:
maxtherabbit wrote on 2020-08-12, 13:29:

People have been successfully putting slocketed cumines in BX boards for decades without issue. Even the fanciest slockets designed for cumine and/or tualatin don't include level translators. (although they sometimes include VRMs for Vcore)

For example the MS-6905 V2.x includes a chip to limit the 'CMOS pull-up voltage', this was added for Coppermine support.
The bus voltage (AGTL vs AGTL+) isn't modified, I find conflicting reports on if the Powerleap IP3 does so but anyone using an interposer for Tualatin support will be using the higher voltage.

I'm not saying there is nothing to your claim, it sounds plausible there is a mismatch going on. But this was a super popular mod over the years and I would think there would be at least some anecdotal reports of chip failures by now if it was actually damaging them.

Reply 9 of 10, by darry

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maxtherabbit wrote on 2020-08-12, 13:29:

People have been successfully putting slocketed cumines in BX boards for decades without issue. Even the fanciest slockets designed for cumine and/or tualatin don't include level translators. (although they sometimes include VRMs for Vcore)

Besides the PowerLeap one PL-iP3/T, are you aware of any others with a VRM for Vcore ?