powermac G3 Beige G4 Upgrade

[jamesmd]

I've just acquired a beige G3 tower and from what I remember the PCI PowerMac G4 CPU should fit straight into this? Am I correct or do I have to buy an upgrade kit. 

Also what is the Max RAM this machine will take? 

Thanks in Advance  

 

[CC_333]

The CPUs in the PCI G4 and B&W G3 are freely swappable (excepting any possible issues with firmware and such), as they use the exact same logic board and architecture (a variant of early G4 was specifically designed to be directly pin-for-pin compatible with G3s, if I remember correctly). Whether the PCI G4's CPU is compatible with the beige G3, I can't say.

Also, the max RAM for the beige G3 is 768 MB in the form of 3x256 MB PC66PC100 DIMMS.

c

 

[Unknown_K]

The FSB would probably be different. The G4 400 with ZIF socket has 100FSB, the G3 beige FSB is 66mhz (some models might use a funky 83mhz). SO while the CPU will fit the bus speed will be an issue.

 

[omidimo]

If you are feeling crazy, you can overclock the old gal. 

I'd say your best bet is to look for old upgrade kits on eBay there are compatible. I got a new Sonnet G4/800Mhz for $90 recently.

 

[Bunsen]

The ZIF socket CPU module from the G4 PCI will fit, yes.  The later modules will not.  You'll need to make sure you have the firmware updated (or downgraded, I forget), which you'll need to do in OS 9.

And you'll need to set the correct bus speed and multiplier on the module DIP jumper header.

The best place to look for the correct procedures for this is xlr8yourmac.com, if you can find their old Beige G3 system page / FAQ.

 

[trag]

Wasn't there some issue with G4s in the Beige G3? Part of Powerlogix's marketing for their fast G3 ZIFs was that they didn't have the problems that G4s do/can.

 

[TheWhiteFalcon]

There might be, though that may be the Pismo.

The early G4 is just a G3 with AltiVec bolted on, so unless you have tasks specifically enhanced by the Velocity Engine I'd go for raw clock speed (i.e. A fast G3) over a slower G4.

 

[flecom]

The CPUs in the PCI G4 and B&W G3 are freely swappable (excepting any possible issues with firmware and such), as they use the exact same logic board and architecture (a variant of early G4 was specifically designed to be directly pin-for-pin compatible with G3s, if I remember correctly). Whether the PCI G4's CPU is compatible with the beige G3, I can't say.

Also, the max RAM for the beige G3 is 768 MB in the form of 3x256 MB PC66PC100 DIMMS.

c

the logic boards are not physically compatible though right? can you put a pci g4 board in a beige g3 tower?? that would be a fun hack

 

[jamesmd]

Thanks for the replies guys! Going to have a look for a cheap ZIF G4 CPU and have a play I have 768MB of RAM fitted now. Lets see if I can get Leopard on this thing! 

 

[waynestewart]

I never tried a G4 ZIF but a 1ghz G3 is pretty nice

 

[Unknown_K]

ZIFs are getting harder to find in an decent speed, I think I have a 400 something or other G3 in my G3 Beige tower.

 

[Powertrip]

I also got one of those 800MHz G4 ZIFs from the UK recently.  The problem with using faster CPUs was the voltage regulator module (VRM).  The Raytheon VRMs are good to go.  The other brand will be hit or miss.  the ZIF CPUs from the G4s will work fine even though they were designed for a faster bus.  Basically it will be working LESS hard in the G3MT. There is a guide on jumper block settings for desired speeds so you can get the G4 back to its 400MHz clock rate.