Two G4s in a beige!

[Irinikus]

Did this work? What combinations have you tried? I don't think a pair of G3 CPUs would be different from G4s. A G3/G4 combination might be interesting too. It looks like the adapter has a separate power supply for the second socket, so the voltages for each CPU can probably be different.

I haven’t tried it with the Yikes CPU yet. There was a issue with the shipping for Germany, so the order was cancelled.

I tried to get it to work with a G3 in the second slot. The machine posted, and gave the gong and the Happy Mac image, but the OS wouldn’t come up. I was attempting to run the CPU’s at different frequencies though, which may have had an impact. I would imagine that you’d have the greatest chance of success with a matched pair of CPU’s installed.

The option that I really want to try is another XLR8 MPE in the second slot, with both CPU’s clocked @ 500MHz, as you apparently only get optimal performance out of it with MPE CPU’s installed.

 

[herd]

Thanks for the reply. You may be the only person running one of these adapters. If you're in the mood to tinker, I have more questions:

How hot does the apple power module run with the 500MHz G4? Some of these were reported to be a bit weak or prone to failure.

Does the adapter work with a single CPU and the molex disconnected? If so, this could mean that the molex is only to provide power to the second CPU.

Does the adapter work with a single G3 installed?

Does that computer have open firmware? If so, it might be easy to read the contents of the EEPROM on the adapter.

 

[Irinikus]

According to the manual, the molex adapter needs to be connected whether running with a single or dual CPU.

Here’s someone else had issues with a 300MHz G3 CPU from a beige system in an XLR8 card:

 

[Powerbase]

According to the manual, the molex adapter needs to be connected whether running with a single or dual CPU.

Here’s someone else had issues with a 300MHz G3 CPU from a beige system in an XLR8 card:

View attachment 91359

I don't think I've ever come across an Apple ZIF with a fixed anything.

 

[Irinikus]

He was just speculating on the cause, but there are issues fitting G3 CPU’s into these cards.

 

[Irinikus]

If it takes too long to get a XLR8 MPE card, I may try a 500MHz SONNET ZIF G4 CPU in the secondary socket.

 

[Byrd]

Sonnet G4s are more "locked" than Apple models, I think you'd have less success trying one.

 

[Irinikus]

Sonnet G4s are more "locked" than Apple models, I think you'd have less success trying one.

Thanks for the advice!

 

[Coloruser]

The G3 has only very limited multiprocessor support and I donˋt think a G3 and G4 Tandem will really work - let aside the socket fit.

the BeBox and the Pios One had multiple G3 CPU support - but that was a heck of extra hardware to get it to work (and never under Mac OS in the case of the CHRP PIOS one).

 

[herd]

I don't think any multiprocessor features are used by the ZIF logic boards, which is part of what makes this dual adapter interesting. So in this case a G3 or G4 should be equivalent, and the XLR8 drivers allow some software to use the second CPU.

The CPU modules have pins to select the speed, voltage, and module ID. I've seen these used in different ways. It looks like the XLR8 G4 has jumpers right on the module, probably for speed. Others have resistors installed, or switch blocks. Sonnet uses a special micro-controller with its own software to control them. Also, some have an EEPROM installed (which I think is mostly to configure the external cache). So the varying degrees of being "locked" has to do with how these pins are handled. i.e. whether they are routed to a jumper block on the logic board, or somehow set on the module directly with no connection to the logic board, etc.

So with the dual adapter, there is also a potential for conflicting settings depending on how the pins are connected inside the adapter. CPU modules with their own switches/jumpers/micro-controllers may have the best chance of working, without knowing what the dual adapter is doing. The voltage pins are used to tell the power supply what voltage to send to the CPU. This why I was asking about the molex. If one CPU gets power from the logic board, and the other CPU gets power from the molex, then they could be different. If the molex powers both CPUs, then which socket tells the power supply what to do?