Not likely the PSU. My newly built system has a 650w PSU and yet...
I am having similar problems in that some USB 2.0 devices work and some don't. I don't have any USB 3.0 devices to check those yet. I am also having other known issues with the MB.
I think SOME of the problems are solved by updates to the BIOS and drivers...but I am still doing research via ASUS forums and support. However, some of the information is contradictory and some of the steps required for the MB are exasperating; such as clearing the CMOS after doing anything/everything?
Not yet...I just finished downloading the updates and plan on doing BIOS and driver updates tomorrow. Shouldn't I flash the BIOS first? And then install updates? And according to some on ASUS forums you must reset CMOS with each added device and other exotic steps?
Weird though is that some devices work fine out-of-the-box with P8Z68 V/GEN3 and some don't work at all? And some of the devices are recognized by the BIOS and don't function?