Trouble Replacing Sonnet Upgrades with OEM CPU

[broots]

Would love some help with this since I am probably missing something simple. I'm having trouble with two AGP PowerMac G4 Towers, one Sawtooth and one Quicksilver. Both had been upgraded with Sonnet CPUs and work fine with those. I ordered replacement CPUs that match the machines original specs, a 733MHz for the Sawtooth and a 867MHz for the Quicksilver, but neither machine will boot with the new matching CPU installed. The machine turns on, fans run, but no startup chime and no image on screen. Doing a PMU reset doesn't help. If I swap the Sonnet cards back in they both boot up as normal.

What am I missing here? Appreciate any ideas!

Thanks

 

[ervus]

Pictures might help. Isn't the Sawtooth aka the "AGP Graphics"? I think those have a 100MHz bus so a 733MHz CPU would not be original. The 733 could be from the Digital Audio or the Quicksilver. The 868MHz CPU should work fine in the Quicksilver...

Power Mac G4 - Wikipedia

en.wikipedia.org

 

[broots]

Pictures might help. Isn't the Sawtooth aka the "AGP Graphics"? I think those have a 100MHz bus so a 733MHz CPU would not be original. The 733 could be from the Digital Audio or the Quicksilver. The 868MHz CPU should work fine in the Quicksilver...

Power Mac G4 - Wikipedia

en.wikipedia.org

Yes! Here are photos of the specs from the back of the towers. From what I can tell both the Digital Audio and Quicksilver have a 133MHz bus so I would expect them to work with 733MHz and 867MHz G4 daughter cards.

The previous owner installed the Sonnet cards so I'm not familiar with the process involved to get those working. I'm wondering if anything would have been reconfigured that I would have to revert for these CPUs to work?

 

[ervus]

I was talking about the CPU you're trying to use and its installation. For example, here's a picture I found of a 733MHz Digital Audio CPU:

 

[broots]

Got it! These are the two CPUs. From the eBay listing they are both for Quicksilver PowerMacs. Parts numbers from the listings are 820-1314-A for the 733Mhz CPU and 820-1344-A for the 867MHz.

 

[broots]

OK! I have sorted it out. The Quicksilver tower I installed the 867MHz into is now working, just had to move the RAM to a different slot. The Digital Audio tower needed a bit more work to run with the 733MHz Quicksilver daughter card. The fourth mounting point on the daughter card needs to be supplied with 12V power to run. Because there is no post for this on the Digital Audio logic board I had to run a cable from one of the molex connectors like in the image below.

Am now up and running!

 

[r6mile]

OK! I have sorted it out. The Quicksilver tower I installed the 867MHz into is now working, just had to move the RAM to a different slot. The Digital Audio tower needed a bit more work to run with the 733MHz Quicksilver daughter card. The fourth mounting point on the daughter card needs to be supplied with 12V power to run. Because there is no post for this on the Digital Audio logic board I had to run a cable from one of the molex connectors like in the image below.

Am now up and running!

View attachment 944267

What is that molex to 12v cable you have going to the daughtercard? I'm looking to do the same thing, put in a QS CPU in a DA logic board.

Also, how come you decided to remove the Sonnet upgrades?

 

[broots]

What is that molex to 12v cable you have going to the daughtercard? I'm looking to do the same thing, put in a QS CPU in a DA logic board.

Also, how come you decided to remove the Sonnet upgrades?

Hi r6mile! The Quicksilver logic board has a fourth mounting point for the CPU daughter card that supplies an additional 12v. This 12v supply is missing from the Digital Audio machines and must be supplied for the CPU to run so I went ahead and tapped into into the yellow 12v line in a spare molex connector.

 

[r6mile]

Hi r6mile! The Quicksilver logic board has a fourth mounting point for the CPU daughter card that supplies an additional 12v. This 12v supply is missing from the Digital Audio machines and must be supplied for the CPU to run so I went ahead and tapped into into the yellow 12v line in a spare molex connector.

Thank you, yes I've learned that's the case, but did you 'make' that adapter (with the yellow cable) going from molex to the 4th mounting pin on the CPU, or did you buy it ready made from somewhere? Sorry if it sounds like a basic question but my electrical knowledge is pretty basic.

 

[broots]

I did make my own adapter which is not as pretty as the one in the photo above. The image is from a post I found on Reddit with the description "I ran the 12V line from a molex adapter I made and used a ring terminal, nut, washers and bolt to recreate the 'fourth' post that is missing from my Digital Audio. You also need to update the firmware of the Digital Audios logic board to 4.2.8 from an OS9 partition." Personally I didn't need to update firmware for the daughter cards to be recognized.

To answer your earlier question I pulled the Sonnets because I am hoping to get them running in a couple of G4 Cubes I have been upgrading.