FW800 Help Needed


macrumors 6502
Original poster
Mar 31, 2012
Edmond, OK
I'm at a loss for a solution to my FW800 external drives operation.

I have 2 working FW800 drives. Had a 3rd(seagate) that quit working FW and only worked USB2.0 It was under warranty, so Seagate sent me 2 other flexes to replace the original. Same problem.
Ok. I ordered 2 miniStacks from OWC for its FW800 ports. Same problem.
Have tried different cables, no go.
When I plug the drives in (individually or chained to the working drives) FW800 only, the Mac just freezes and nothing. Have to reboot.
Every thing shows a go (power on spin up) but nothing.
I can't figure it out.

Thanks for finishing this tome. Suggestions?


macrumors 68030
Feb 10, 2008
I forget how to check the FW connection logs, but I had a troublesome FW 800 issue that was a challenge. I eventually found two issues. One of the devices was bombarding the FW port with interrupts/errors and that was locking up the Mac. There was one bad/noisy cable that caused similar issues. Both together was a challenge to figure out.

I would also suspect your mac port or FW controller.

You should take a look at the logs, its been so long that I forget the detail... but someone should jump in here.


macrumors 6502a
Jun 10, 2007
There was a time when some Firewire ports on Macs would kill devices. Not sure if it was a bug in the firmware or implementation of the devices bridging boards.


macrumors P6
Feb 20, 2009
Try this:

Shut down the iMac and disconnect all firewire devices.

Restart the Mac and let it boot up.

When you get to the finder, open System Profiler or System Information (same app, different name depends on which version of the OS you're using).

Towards the upper left, click "FireWire", then observe to the right.

Does it show the presence of a firewire bus?
Or do you by chance get the notice, "no firewire ports found" ????

Why I'm asking you to try this:
I have a 2010 MacBook Pro, on which the firewire port stopped working. MacBook was still under warranty, so I had the logic board changed out. Firewire port worked again, but after several more months -stopped- working (rcvd the "no firewire ports found" alert, as above). I didn't use firewire with the MacBook and it was now out-of-warranty, so I let it go.

Some months later, I upgraded the OS on the second partition on the MBPro to Lion (10.7). After doing this, I checked System Profiler, and amazingly, the firewire port had "come alive" again!. In fact, when I rebooted back to OS 10.6.8 (main OS on that unit), it was alive there, too.

My guess is that the OS "loads a kext" at bootup that:
1. identifies the Mac as having firewire ports, and
2. establishes a connection to them.

Somehow this had been interfered with earlier, and the firewire ports weren't being recognized at bootup as they should have been.

Perhaps an "SMC reset" is in order....

Other thoughts:
Were you previously relying on "firewire bus power" to power all your drives?
Could you have exceeded the maximum amount of bus power the firewire port could supply?


macrumors 6502
Original poster
Mar 31, 2012
Edmond, OK
I've heard about bus powered FW having a problem. Mine all haves their own power supplys.

There's not a max length for daisy chaining is there?Mine's not long.


macrumors 6502
Original poster
Mar 31, 2012
Edmond, OK
Ok, Update"

Called Applecare, even though my coverage expired earlier this month. They granted me a special assistance, which I'd hoped they would.

Went through several basic Lvl 1 steps, which I had alkrewady tried. Nada.
So, chose a store visit appointment tomorrow (wed) morning. Had this problem before the expiration, but couldn't 100% replicate it.