i just want to share my personal experience.. i have an arduino uno and the 5v 8 module relay as well.. i'v been using an adoptor of 5v-2amp as power supply.. unfortunately my ATMEL chip was been damaged.. so i buy again a new arduino uno.. i removed the damaged ATMEL chip and placed the new ATMEL chip and its working.. so i conclude that the ATMEL chip really stops working.. i bought another 5v-2amp adoptor and dedicate this to power the relay.. so i have 2 power source 1 for arduino and 1 for the relay.. wire the GND-IN1-IN2-IN3-IN4-IN5-IN6-IN7-IN8-VCC through the respective pins of the arduino if you wish to use it all.. at the lower right of the relay remove the jumper in VCC JD-VCC... wire the GND to the NEGATIVE and JD-VCC to the POSITIVE of your 5V adoptor.. this will power the coil of the relays.. till now mine is still working good..