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G'day. Posted in Conquests.. probably should be here.

 

I've got a 7500/100 and a fair few G3 Zif cpu's around. Anyone recommend a zif carrier card to look out for and buy?

 

Anyone suggest where I could buy one from?

 

Best Wishes,

Al

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I'd say keep an eye out for the XLR8 MACh Carrier ZIF.  The site below is in French but it gives a pretty good rundown of the card and what it can do with the right CPU.  The limitations of the card (topping out around ~500MHz) are reasonable since you're probably not going to find a ZIF CPU, G3 or G4, any faster than that.

http://macbidouille.com/articles/test-de-la-carte-mach-carrier-mpe-de-xlr8/page1

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I don't think that any of the ZIF carriers actually have a CPU frequency limit.  There's a limit to have fast of a clock signal they can supply to the CPU, but what the CPU does with it afterwards (multipliers) won't be (entirely) controlled by the carrier card.

 

That said, that limitation was probably written by marketing, back when the top CPU:bus multiplier was 10:1.    So XLR8 figured, "well, we can supply a 50MHz clock, and the highest clock mulitplier is 10:1, so our top speed must be 500 MHz."   And the jumper/switch settings for the clock muiltiplier are on the carrier card.

 

The above does not reckon with the fact that later CPUs redefined some of the clock multiplier codes/pin settings to mean different, higher multiples, nor did it take into account the chips which are capable of a soft multiplier setting (PPC750fx, PPC750GX).

 

In my opinion XLR8 probably had the best, most developed carrier card technology, but ultimately, a carrier car is pretty simple.    It must supply a clock signal (generally between 40 and 50 MHz (although up to 65MHz can be useful), it must have onboard power regulation that honors voltage level pin settings from the ZIF, and it needs to have switches/jumpers to properly bias the CPU clock multiplier pins on the ZIF card.

 

PowerLogix made a smaller, simpler carrier card that seems solid.   I think Formac also sold one.  And NewerTech sold a few as well.

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  • 5 months later...

Not to bring up a dead thread, but Powerlogix only sold up to 1.1GHz G3s.  I believe if you held down option when opening up their CPU Director software, it would give you access to the higher multiplier settings.  You could then overclock it to 1.2GHz or beyond.

 

I actually have some results on Geekbench from when I ran my B&W G3 at 1.2GHz.  It would eventually cause issues if it ran at that speed for a while, another one I had would just immediately freeze, though.

 

BTW, I personally use a Powerlogix Z-force carrier in my Powerbase (one of only ones, aside from first gen XLR8s that supported it).  There isn't really much to the card.

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Yes, the carrier cards are fairly simple in principal.    They take all the CPU signal lines and translate them (mechanically) from ZIF socket to edge connector.   The Carrier card also provides an adjustable voltage regulator that takes its level based on the voltage signal pins on the ZIF.    Finally, the Carrier card provides the system base clock and provides a Clock Buffer chip which splits the Clock into about 6 equal clocks, one for the CPU on the ZIF and five (IIRC) others that are routed to the motherboard through the edge connector.

 

So power and clock.  Those are the two things that a ZIF lacks that an edge connector style Apple CPU board provides.

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