Yeah sounds like power issue
This is taken from the official site

Model B owners using networking and high-current USB peripherals will require a supply which can source 700mA (many phone chargers meet this requirement). Model A owners with powered USB devices will be able to get away with a much lower current capacity (300mA feels like a reasonable safety margin).

I have a 1500ma psu and got a wired xbox controller, keyboard and ethernet plugged in and no issues.