This message was posted on behalf of Intel Corporation
Thanks for your interest in the Intel Edison Platform.
It all depends what are using, if you are using just the Compute Module you should provide between 3.15-4.5 V like you said. And if you are using the Arduino expansion or the Mini Breakout Board you should provide a power supply between 7-15 V. Check the datasheets attach below.
You should respect this voltages boundaries, otherwise it may result in a permanent damage to the board. Hope you find this information useful.
1) Hardware Guide for the Intel® Edison Compute Module Section 4.12.
2) Intel® Edison Kit for Arduino* Hardware Guide Section 4.
3) Hardware Guide for the Intel® Edison Breakout Board Section 2.3.