12-05-2009, 10:05 AM

I've been having a chronic problem with any USB external drive connected to my Mac Pro. Wondering if anybody else here has experienced the same troubles.

Appears to happen whenever I'm doing something intensive with the drive (i.e. moving a large file, editing video off of it, etc.).

I haven't been able to figure out what the problem is. Perhaps it's the USB ports themselves, or maybe it's a power issue (I don't currently have a UPS for my tower).

Anybody else seen this before?

12-05-2009, 01:29 PM

Is that external drive - any one - powered from the USB port itself? Mac USB does not always provide reliable power supply to external devices unless their demand is minimal, eg. keyboard and mouse. A UPS for the Pro won't make any difference to this issue.

I suggest you invest in a quality powered external hub, or use mains-powered external devices, especially for the "intensive" work.

12-05-2009, 03:24 PM

The external drives (1 x 500GB, a couple others at 1TB) all have power adaptors, not USB powered. And I've tried using a USB hub, but to no effect.

The building I'm in is VERY old and is pretty bad with dirty power, so I figured that could be the issue, but recently tried using a power distributor. Again, no effect.

It's starting to sound like the problem is with the USB ports themselves, so I may have to get them looked at.

12-05-2009, 03:36 PM

Boot, and then run a hardware check from the Install Disk 1 > Disk Utilities [this is better than using DU from within the MacOS]. An analysis may show a USB fault. If so, it's likely to be on the motherboard, which, as I think you hint at, is a job for an expert.

Re the "dirty power", if your Mac Pro is operating without faltering (excluding the USB issue), then the mains power is unlikely to be the cause of USB failure.

Are your external drives firewire-capable? If so, try that avenue to see if you can get around the USB failures.