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The beige G3 logic board that wouldn't die (Beige G3 µATX build)

demik

Well-known member
Hello,

This is a little bit of a blog post, if this is more suited to "The Lounge", please let me know.

This is the story of my longest running Macintosh (nicknamed Pulse), which is still running 24/7 after 17 years.

Intro

A while ago, circa 2002-2003, an apple reseller gave me a dead G3/233 Desktop. When I said "dead", I mean it wouldn't boot and half of it was missing:

- Top of the case was missing

- The whisper personality card shield was missing

- Case was bent, was probably dropped 

- No RAM

- No HDD, No Optical Drive

Repair procedure

As I needed a new file server (my Performa 6400 was dying), I though it would be a good idea to repair it. The Mac was not starting, but after trying with RAM borrowed from a Pentium III and an ATX PSU, I heard the chime but the display cas scrambled.

The VRAM extension card was defective, I managed to reflow it in a kitchen oven, and put it later on my MT/300 G3 as VRAM isn't really needed on a server.

There you go, it was sort of alive again. 

I needed some sort of storage backend and decided to go with a combo of SCSI and hardware SATA RAID (SATA for OS + Files, Using old SCSI drives as backup). I was so impressed with the performance that I upgraded the CPU with a Sonnet Encore G3 500/1M (https://everymac.com/upgrade_cards/sonnettech/encore_g3/encore_g3_500.html). System bus was overclocked at 83 MHz (83 * 6 = 500 MHz) 

It ran for a few years on a bad ATX case stacked on a top of rack, thinking it would die a few months after. 

New Case / Rebuild

More than 10 years later (2016), being impressed that this Mac was still running, I decided to put it back together in a more clean build. The chosen case was a white cube : Corsair Carbide Air 240.

Corsair%20Carbide%20Air%20240.jpg


The motherboard was almost fitting without too much issues

Motherboard%20fit.jpeg


I had to cut a little bit of the backpannel to fit the SCSI Connector :

SCSI%20Connector.jpeg


It got a new PSU for this occasion.

Current configuration

The current configuration is as follow

- MB : Apple PowerMac Gossamer Logic board

- CPU : Sonnet Encore G3 500/1M

- Bus : 83 Mhz

- RAM : 640 MB

- OS : Mac OS 8.1 (Bootstrap + Maintenance) + Linux Debian 8 (Custom Kernel)

- SCSI : Onboard SCSI (for external disks) + Adaptec PowerDomain 2940UW (flashed from a PC Card)

- SATA : Bootable Silicon Image 3112 + Hardware RAID Module (stolen from an external RAID Array)

- High end ATX PSU (don't remember which one, probably Enermax or Corsair branded)

An inside view:

- The blue led board is the hardware SATA RAID Controller

- The CPU coller comes from an Athlon XP system, with the fan removed

Inside.jpeg


Usage

Today it's still used and has no time to sleep : It's used as a file server (Netatalk), DLNA Server (Audio), DNS cache, DHCP server, SSH Gateway and Syslog server.

It gained an Apple Logo on a front, courtesy of a broken Quadra 800 Front panel

Front%20logo.jpeg


Here is a little Linux output :

Code:
 demik@pulse  ~  cat /proc/cpuinfo 
processor	: 0
cpu		: 740/750
temperature 	: 27-29 C (uncalibrated)
clock		: 501.150000MHz
revision	: 131.2 (pvr 0008 8302)
bogomips	: 33.41
timebase	: 16707866
platform	: PowerMac
model		: Power Macintosh
machine		: Power Macintosh
motherboard	: AAPL,Gossamer MacRISC
detected as	: 48 (PowerMac G3 (Gossamer))
pmac flags	: 00000000
L2 cache	: 1024K unified pipelined-syncro-burst
pmac-generation	: OldWorld
Memory		: 640 MB


Conclusion

If I can think of a series that can continue to run on standard "PC" parts, this is the Gossamer Logic Board. Everything can be found easily even today. My PowerMac G5s are dying left and right, and I've yet to see a Gossamer logic board to fail. Sure, there is the occasional VRM cap to replace, and I need to replace the fans soon. (bearings are shot)

The PPC750 is also a very simple and stable CPU. One of the best designed CPU of it's erra. It has few bugs online modern x86 counterparts. Thats also part of why it's running on Mars since almost 10 years (https://en.wikipedia.org/wiki/Curiosity_(rover))

Will keep this one up for science until the motherboard dies :)  

 

CircuitBored

Well-known member
This is tremendously cool, possibly the best-loved G3 ever when it comes to your dedication in prolonging its life. I love seeing a machine that's lived a long and useful life.  

I'd be wary of survivorship bias though: I know from personal experience that the Gossamer boards can develop flaky solder connections on the expansion slots over time. That said, I've seen it suggested a few times that running a computer 24/7 tends to be better for its longevity than turning it off at the end of each day and allowing it to cool down. My Quicksilver G4 ran flawlessly 24/7 for over a decade yet immediately became an unreliable heap once I put it on a daily power plan. The solder on the RAM slots had cracked and wreaked havoc. 
 

The G3 is such a glorious halfway house between technological eras. The step up from the 604 was immense yet the G4 came and stomped on it so soon after its birth. I'd love to see a homebrew logic board for G3s emerge some day - that would be such a fun low-power tinkering machine. 

 

demik

Well-known member
This is tremendously cool, possibly the best-loved G3 ever when it comes to your dedication in prolonging its life. I love seeing a machine that's lived a long and useful life.  

I'd be wary of survivorship bias though: I know from personal experience that the Gossamer boards can develop flaky solder connections on the expansion slots over time. That said, I've seen it suggested a few times that running a computer 24/7 tends to be better for its longevity than turning it off at the end of each day and allowing it to cool down. My Quicksilver G4 ran flawlessly 24/7 for over a decade yet immediately became an unreliable heap once I put it on a daily power plan. The solder on the RAM slots had cracked and wreaked havoc. 
 

The G3 is such a glorious halfway house between technological eras. The step up from the 604 was immense yet the G4 came and stomped on it so soon after its birth. I'd love to see a homebrew logic board for G3s emerge some day - that would be such a fun low-power tinkering machine. 


Thanks for the input ! I only saw the flaky connections on G5 and some late G4s, will keep an eye on it. 

You are spot on with the 24/7 longevity. Maybe that's why this one is still running. Another important thing is that there is very few heat produced by a gossamer logic board. Power Wall consumption is under 50W on my system.

Heat play a major role on solder connections.

Unfortunately this is less true on today computers, because they heat a lot more (excluding Apple M1) and with dynamic power features it's like you are putting on a power plan multiples times a day...

As for the home-brew logic board, it was done by the Amiga Community under the Pegasos name (https://en.wikipedia.org/wiki/Pegasos

The G3 processor doesn't look like to be produced anymore. The G4 is (MPC7448 at least), but prices are a bit on the expensive side (up to $500 a single unit). Then there is the soldering problem, soldering BGA components is kinda hard (well there is the oven trick, but soldering $500 components in your kitchen oven isn't something that many will do).

That would be cool, but technically difficult for a home-brew board.

 

cheesestraws

Well-known member
This is really nice.  Especially the Apple logo.  Well done.

Will third the fact that power cycling is enormously harder on machines than just running them all the time.  I've always assumed this is thermal stress but have never looked into it deeply.

 

joshc

Well-known member
This is really interesting. I have often wondered about how to best adapt an ATX case to some of these Mac logicboards. I really like your implementation, thanks for sharing it!

 

demik

Well-known member
This is really nice.  Especially the Apple logo.  Well done.


Thanks. I'm bad at cursing thing straight though...

This is really interesting. I have often wondered about how to best adapt an ATX case to some of these Mac logicboards. I really like your implementation, thanks for sharing it!


Thanks ! From my experience G3 and early G4 Motherboards are easy to adapt, though you will need to do new fixing holes.

Those crazy Amiga fans! Thanks for the heads up on that - I'll get on the hunt. It'll probably take half a decade but I'm sure one will show up on ebay eventually...


Speaking of which, if you need a home-brew G3/G4, maybe you can start with a G3/G4 motherboard ? They are plenty of Sawtooth and similar motherboards for like $10 on eBay and QS 733 MHz CPUs are around the same price. They play with ATX PSU just fine if you do an harness adapter.

 

Cory5412

Daring Pioneer of the Future
Staff member
This is really cool, although I'll admit I was a little sad when I got to the part where it's doing AppleShare services using Netatalk instead of AppleShare IP or even Mac OS X/Server 10.2.

What's the RAID module do? Are you presenting a larger volume to the SIL3112 or does it mostly just offer SATA splitting?

I have thought about doing something similar to this, although using a dA/QS motherboard and several SIL3112s, mostly to keep the QS02 I'm running AppleShare on going a bit longer.

 

Kaa

Active member
This is very cool! I actually just order a bench frame for my G3 Tower MOBO and plan on something similar. Right now it runs an IDE to Compact flash for a drive. Can you elaborate any on your SATA setup for your system? I would love to run SATA drives on this computer.

 
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