[nintendoeats]

I have been going through a bit of a saga with an SGI Indigo2

First, I ordered an Indigo2 off ebay as-is with the following description:

You are bidding on;
Silicon Graphics Indigo 2 CMNB007 (1992)
Model # CMNB007
This item is ***VINTAGE***
          (1992)
           AS IS, working
  
           2 Broken Clips on Front cover

           Silicon Graphics MotherBoard
           200MHz IP22 CPU Board R4400
           IP22 ASSY 030-8102-008 REV.B
           W/Heat Sink Card Attached
           89749:5
           22228487
           W/4x 8MB NEC SIMMs RAM (Bank B)
           72p 80ns 24c 1x4 Parity FPM SIMMs
           MC-422000A36FJ-80
           9302XE 94V0
           W/4x 32MB Kingston SIMMs RAM (Bank C)
           72p 60ns EDO SIMM  5v Parity
           KSG128/R40
           Kit of 4-03217
           W/Graphics board
           GR3-XZ (X/Z Graphics)
           VB2 ASSY 030-8105-005 REV C
           Assy No.030-8103-005 REV C
           VT4493
           W/5.25 SCSI Drive Bay
           FH 5.25 BKPLN ASSY 030-8114-004 REV.B
           91766 04
           W/Seagate Legacy
           Fast SCSI HDD
           535 MB
           ST3610N
           SGI Part No. SGI-9410828-B
           952002-031

When I read this, I see 200 MHz R4400 w/ heatsink card attached, and I figure I'm getting a 200 MHz CPU. What I actually got is a 100 MHz R4000. I'm still talking to the seller about this, in addition to some damage sustained during shipping.

In the meantime, because 100 MHz is really quite slow, I ordered a 250 MHz R4400

This processor was removed from a Purple Indigo2  - CMNB007Y125 that would not boot

The new CPU part number is 030-0808-001, which SGI depot lists as a 250MHz CPU. I just plugged it in; while it certainly works, it only reports as 200 MHz (2MB). So now I'm wondering, is my motherboard limited to 200 MHz? Do I need an updated PROM to use the full 250 MHz? I haven't seen anything about that anywhere, and I feel like I've done a fair bit of reading.

[jan-jaap]

You almost certainly need a newer PROM chip to correctly identify this CPU. 100MHz R4000 was the first, and 250MHz R4400 the last CPU available on these systems.

However, the CPU speed isn't set by the PROM, it merely shows it. If you can boot it into IRIX, it will probably show the CPU for what it really is.

Also, you might want to double check the part# of the CPU card, early R4000 systems had the tendency to report the external clock speed rather than the internal (core) clock. That's why 50MHz Crimsons have a 100MHz CPU, and 75MHz Indigo R4400's really have a 150MHz CPU.

[nintendoeats]

Thanks for the info! After work I will pop into IRIX and see what is reported in the OS.

The 100 MHz (which is in front of me) actually says R4000SC-50 on the chip, so I am pretty confident that was reported correctly.

[nintendoeats]

It does indeed show as 250 MHz in IRIX, huzzah!