Model A1225 / Mid 2007 and Early 2008 / 2.4, 2.8, or 3.06 GHz Core 2 Duo processor

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replaced both RAM chips. upgraded to Yosemite, now no firefwire bus

After increasing the RAM to 6 GB. One 4 GB and one 2 GB modules. I then upgraded my OS from Mavericks to Yosemite. Now none of my firewire hard drives are loading, and the system profiler says firewire devices cannot be listed. I have reset the NVRAM and this did not help.

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are you use the right speed of ram?

does it show up in disk utility? did you format them when you were doing the upgrade?


While the OP altered the RAM it would not be the factor here as to why the OS upgrade from Mavericks to Yosemite would cause the FireWire port to stop working.


I have the correct DDR2 / 800mhz that this model calls for.

There is nothing in the installation instructions that mention formatting or how to do that.

I have OS 10.10.4 now.

One of the three drives does show up in the disk utility app. It doesn't mount and disk first aid won't fix it. If I try to eject the unmounted disk it won't let me. One of the other disks tries to mount, and then there are a string of warnings about improper ejecting and disk may be damaged.

Very strange.


That sounds like the power or you pulled the cable while the drive still had pending writes. Apples Disk Utility will only get you so far. I think you'll need something that goes deeper here. I like Drive Genius but there are others out there that will work. Lastly, your drives may need replacing as drives do wear out.


Thanks to all of you for your suggestions and input. After a couple more attempts at re-booting various ways, I decided to disconnect all externals from the computer and start over. After start up I powered up each fire wire drive and let it spin up before connecting it to the iMac. In this fashion, one by one I hooked up the chain of drives. Now everybody shows up in the system report, and there are no funny disconnect notices.

Everything seems to right with the World at this point.

Again thanks to everyone for helping with this "head-scratcher".


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Boot up from the original system installation disk, go to Disk utilities on the second page pull down menu and see if they are still showing up. Which version of 10.10 do you currently have?

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that has nothing to do with firewire.


@Sunny - Mayer's point was if the FireWire drivers got messed up. By using the installer disk which has its own bootable OS one could isolate if the installed OS was damaged. Basically it was a diagnostic approach.


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