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Quad Mac G5 2.5 gH shows unknown device in system profiler

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Quad Mac G5 2.5 gH shows "unknown device" in system profiler with nothing plugged into any firewire port. Why?
Hello, and thank for seeking technical assistance for your Mac .I am Sr. Mac Support Specialist, TD at your service.

Do you still happen to have the same disks that came with your PMG5 Quad 2.5Ghz? I am just checking to see if your were ever provided an Apple Hardware Test disc.

• Also from within System Profiler can you provide me this hardware information for your Power Mac G5 Dual 2.5 Ghz?

• Boot ROM Version:
• SMC Version:
• Serial Number:

I appreciate you providing me this information in order to isolate and work toward resolving your Mac Technical issue. I look forward to your reply. Thanks!


Customer: replied 8 years ago.
The Boot ROM version is 5.2.7f1

Serial Number G85501NAR6W

I din't know what "SMC" is and don't see it listed in System Profiler.

What is SMC ?
Customer: replied 8 years ago.

Anybody home
Hello. Yes I am here.

In System Profiler here is what the Hardware screen looks like:


Now if you don't see this, if you could go into Apple Menu >About this Mac and provide me the Processor that you have. That will help as well.

My reason for asking for this information, is because I need to get an idea of your firmware version, so I can offer rmore assistance to help you on this port connection issue you are having.

My apologies for the delay, just coming online and will be here for most of the day today, so I am going to work with you to help see this through to resolution as completely as possible.

I await your reply. Thanks!

Customer: replied 8 years ago.
SMC Version is not listed in the system profiler. This machine has two dual core 2.5 processors
Thanks for your reply.

Here is what I would like you to try:

If you have the original discs that came with your PowerMac G5 2.5 Ghz
then please pull Disc 1.

• You should have the Apple Hardware Test (AHT) utility on that disc.
- This utility will test all connections on your logic board and provide a
diagnostics for checking on the functionality of the hardware.

This needs to be checked so we can see if there is an actual issue with the Firewire ports on the Power Mac G5's logic board.

If you do not have the original discs including Install Disc1- stop here and reply back to me at your earliest convenience.


• Disconnect all external devices from your computer except the keyboard and
mouse. If you have an Ethernet cable connected, disconnect it.
• Insert the Mac OS X Install Disc 1 that came with your computer.
• Restart your computer and hold down the Option key as it starts up.
A list of available startup volumes appears.

• Click Apple Hardware Test and click the right arrow.
• Follow the onscreen instructions when the Apple Hardware Test main
screen appears (after about 45 seconds).
• Make a note of the error code before pursuing support options.

** If Apple Hardware Test detects a problem, it displays an error code.
If Apple Hardware Test does not detect a hardware failure, the problem
may be software-related.

You can also refer to Apple Hardware Test Read Me file on the Install Disc 1 for more information if needed.

I will be posted, awaiting your reply. Thanks


Customer: replied 8 years ago.
The hardware test does not show a problem
Ok, considering the AHT (Apple Hardware Test) showed no issues

This could be what is called a "phantom FW device issue".

This can be as the result of a 3rd party device which could affect the performance of the firewire ports on your PM G5's logic board.

Now if you are comfortable with going inside a short ways into your Power Mac,
Here are some steps below to reset the PMU on the logic board, to see if this can
aid in removing the "unknown device" message you see in System Profiler

• Pull ALL cables (pwr, USB, etc) and let sit for 10 minutes; reconnect & restart.
• Press the SMU reset button (ONCE) on the logic board; it is halfway between the lowest RAM slot and the bottom edge of the logic board.
• Reset the PRAM:

4) Open Firmware reset for PPC:
After the startup tone, hold down Apple Command key, Option, O & F keys, until the text screen is visible. When text can be entered, type the following commands, followed by the Return key after each line:

Reset-all (the Mac will boot up after this command is entered)
Your Mac should restart and your FireWire ports may be available.

If that does not work, try turning off your Mac and unplug from the main electricity for 15 mins to reset the FireWire ports.

See if this helps the Firewire unknown device issue.

I have a strong feeling, that as long as the unknown device message is not affecting the performance of any of your Firewire 400/800 ports when connecting devices,
this issue may be just that, a "phantom FW device issue".

Let me know if this helps.

I will keep watching for your updates.


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