(...)What connections do you keep open? Logoff your IMs and run powertop again (start it lock screen and kbd and wait 45seconds), if there is no change uninstall apps using the network connection one by one and run powertop in between so you get to know if it changed anything. (...) Is any other widget updating anything on the net? Is a ssh session open? EDIT: could be a router setting you changed, what does it do with wifi offline?