This question is similar to the superuser question "How to check how much power a USB port can deliver", which is answered for Linux and Windows.
How do you check the same on a Mac?
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Sign up to join this communityThis question is similar to the superuser question "How to check how much power a USB port can deliver", which is answered for Linux and Windows.
How do you check the same on a Mac?
The Knowledgebase article Apple Computers and Displays: Powering peripherals through USB contains some general guidelines and illustrates using System Profiler (System Information in Lion) to provide information about the output (according to specifications) of a Macs USB ports.
If you want to test the real world voltage output of a given USB port on an individual Macintosh at a given load you will have to use a test device. (USB Test Circuit)
Simply open About this Mac -> More Info... and go to USB on the left side of System Profiler. You will get current (now power or voltage) in milliAmpere but I guess this is what you need to know. E.g.
USB Receiver:
Product ID: 0xc52b
Vendor ID: 0x046d (Logitech Inc.)
Version: 12.00
Speed: Up to 12 Mb/sec
Manufacturer: Logitech
Location ID: 0xfa130000 / 6
Current Available (mA): 500
Current Required (mA): 98