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Intel-based Macs and FireWire interference (#3): More on not using two bus-powered devices simultaneously

Intel-based Macs and FireWire interference (#3): More on not using two bus-powered devices simultaneously

CNET staff
2 min read

We continue to cover issues with FireWire interference on Intel-based Macs. In many cases, there are problems using two high-powered, or high data-transfer-rate FireWire devices simultaneously.

MacFixIt reader Eric Young writes:

"I can confirm this issue with the internal FireWire 400 bus of the iMac.

"I was preparing to update my image for the (then) new iMac model (PPC, iSight iMac) and discovered that if more than one bus powered FireWire device was attached to the iMac the finder would become unresponsive and both FireWire devices would become unavailable until I restarted the iMac.

"Prior to the change, I could attach up to three bus powered FireWire devices (portable hard drives) to an iMac without issues. After the change, attaching more than one bus powered hard drive was enough to exceed the voltage on the single bus. I have confirmed this with my local Apple system engineer and Apple support.

"The solution is to use a powered FireWire hub.... although the stated work around (to use a powered device as the lead of a chain of devices) should work as well).

As we noted in our previous coverage, FireWire interference is a well-documented phenomenon for PowerPC-based Macs, which often experience issues managing multiple FireWire devices, especially when one or more devices is bus-powered.

There are several suggestions in our tutorial "Minimizing FireWire interference," including the addition of an externally powered FireWire hub, switching ports and more.

Previous coverage:

Resources

  • "Minimizing FireWire interference,"
  • Intel-based Macs and FireW...
  • Intel-based Macs: FireWire...
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