My setup consist a Raspberry Pi 3 model B running raspbian jessie. It is powered through GPIO header by a 5V, 5A switching regulator. I had a HDMI monitor, a flash drive and a USB hub connected with a keyboard and mouse plugged to the RB Pi. It all worked fine while i was using WiFi for internet connectivity.
But once i connect a USB dongle, the HDMI monitor starts to black out randomly. Sometimes 2 minutes after powering up. Sometimes 1 hour after powering up. RBPi do not reboot at any occasion,but i found the key board and mouse not responding at these times.
I checked the supply voltage. But it was stable at 4.975V. I tried changing the HDMI cable, changing
config_hdmi_boost=7, and connecting all the USB devices to the HUB and powering the hub from a separate supply. But nothing solved the problem.
Really appreciate your help since i don't know what is the problem.