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Sourcing a VRM (voltage regulator module) for Pentium Pro motherboard (Micronics W6-LI with 440FX)

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First post, by jormaggio

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I am in the process of building a dual Pentium Pro rig. I've got all the bits pretty well together, but noticed that the motherboard (a Micronics W6-LI) is missing the VRM module required to run the second CPU. The manual only says the "VRM" module is required, but there is no model number or anything like that.

A few questions:

  • Is there a standard to these VRMs or are they proprietary for each board / manufacturer?
  • What would be the best way to try to find one of these modules?
  • Is there a go-to site or person to talk to find these?
  • If I get a busted module, could it be fixed by someone who knows his electronics?

Attached are a few pictures of the board with and without the VRM populated to show the shape of the VRM as well as the socket.

00005.jpg
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00002.jpg
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vrm.jpg
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Reply 2 of 4, by jormaggio

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Predator99 wrote on 2021-02-18, 08:01:

For my PPro board I ordered a
155681-001 Compaq Voltage Regulator Modul
Runs fine, the board is not a Compaq one.

Thanks. They seem to be reasonably priced (and available!) and the connector looks similar. I'll order one and see how it goes.

Reply 4 of 4, by PARKE

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jormaggio wrote on 2021-02-18, 06:54:

A few questions:
[*] Is there a standard to these VRMs or are they proprietary for each board / manufacturer?

In case it is needed some more info:

OVERDRIVE® PROCESSOR SOCKET SPECIFICATION
17.2.3. OverDrive® Voltage Regulator Module Definition
Header 8 is a 2-row, 40-pin shrouded header designed to accommodate a Pentium Pro processor VRM, OverDrive VRM, or a programmable VRM. The OverDrive VRM is used to convert the standard 5.0V supply to the OverDrive processor core operating voltage. Integral OverDrive VRM hold down tabs are included as part of the header definition for enhanced shock and vibration protection.
OEMs who plan to design a custom VRM PC Board to fit into Header 8 should refer to the
AP-523 Pentium® Pro Processor Power Distribution Guidelines Application Note (Order Number 242764).
17.2.3.1. OVERDRIVE® VRM REQUIREMENT
When upgrading with an OverDrive processor, Intel suggests the use of its matched Voltage Regulator Module, which Intel plans to ship with the OverDrive processor retail package. If the OEM includes on-board voltage regulation and the Header 8 for the OverDrive VRM, the on-board voltage regulator must be shut off via the UP# output of the CPU. When the OverDrive processor is installed, and the UP# signal is driven LOW, the on-board VR must never power
on.

Filename
24276401.pdf
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930.47 KiB
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Fair use/fair dealing exception

And info on a Semtech VRM:

Filename
MP60-E-HC.pdf
File size
22.81 KiB
Downloads
95 downloads
File license
Fair use/fair dealing exception
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