Dual G5 32 or 64 bit

I have a dual G5 power Mac. Running lateset version of 10.5. Is it running 32 bit or 64 bit? How can I tell ? How can I change between modes. Both on a temporary and perminate basis. I have a 32 bit PCI card installed that only has 32 bit drivers and I cannot get them to install. Same card in same machine runnig 10.4.11 worked fine.

Posted on Oct 4, 2011 7:00 AM

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10 replies

Oct 4, 2011 8:02 AM in response to jlefevre1

The G5 PPC processor is 64 bit


https://secure.wikimedia.org/wikipedia/en/wiki/Power_Mac_G5


However as you know 32 bit code can run on 64 bit processors, just uses half the registers.


You don't need to worry about switching modes, the OS handles everything.




jlefevre1 wrote:


I have a 32 bit PCI card installed that only has 32 bit drivers and I cannot get them to install. Same card in same machine runnig 10.4.11 worked fine.


The problem is you need the updated drivers to work with 10.5.

Oct 4, 2011 8:12 PM in response to jlefevre1

I am using the updated drivers for the Active Silicon card. They are specifically listed for OS 10.5 on a PPC machine. I am working with Active Silicon and they are the ones who specifically state that the drivers will only install when the Mac is running in 32 bit mode.


Now go back to may original question which noboby seams to read and comprehend.


How do I tell if the Mac is running in 32 or 64 bit mode and how do I force it to run in 32 bit mode. If someone has the answere to that specific question the I would find it helpful. All other theories and comments are off the table so please do not offer suggestions in any other area.

Oct 4, 2011 10:06 PM in response to jlefevre1

That being said, I have found that Tiger is definitely, unmistakably MUCH snappier on my Power Mac G5 Quad.


2.5 GHz Power Mac (PPC) G5-Quad; 16GB RAM; mutant, flashed 550MHz nVidia GeForce 7800GTX, 1,700MHz 512MB VRAM; ATTO ExpressPCI UL5D LP SCSI card; Mac OS X Tiger 10.4.11 and Leopard 10.5.8 boot drives; Spotblight, Dashboard and Time Machine permanently disabled; dual 22" CRT monitors; USB wireless 'n' available but connected to the Internet via wired Ethernet; FW flatbed scanner; 2 SCSI scanners (one tabloid-size transparency scanner and a film scanner); various internal & external HDs; FW Epson 2200 and Ethernet Samsung ML-2850ND printers; 2 X Back-UPS RS 1500 XS units.

Oct 5, 2011 2:48 AM in response to jlefevre1

How do I tell if the Mac is running in 32 or 64 bit mode and how do I force it to run in 32 bit mode.

In a PPC Mac, OS X is running in 32 bit mode, period.

That is default and there is no compatible PPC 64 bit kernel for 64 bit OS X.


There are 64 bit components within the architecture, but software function is capped in the kernel at 32 bit.


You likely cannot force 64 bit in a PPC Mac in any OS that it can run, but you can try if you want


To try to boot 64 bit kernel on a Mac, find and edit this file:

/Library/Preferences/SystemConfiguration/com.apple.Boot.plist

Locate:

<key>Kernel Flags</key>
<string></string>

and change to:

<key>Kernel Flags</key>
<string>arch=x86_64</string>


No warranty stated or implied with the above hack.

Proceed at your own risk.

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Dual G5 32 or 64 bit

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