I bought a brand new Raspberry Pi. It came with a 5v ~ 1A power adaptor and a mini-usb cable. I plugged it in and plugged in my cat 5 into the ethernet port. The raspberry powered up but the Ethernet LEDs were not lighting up. After trying a lot of different things I decided to replace the mini-USB cable with a phone-charger cable. And it worked!! The ethernet LEDs came on. Mind you, I was still using the power adaptor that came with the Rasp Pi, I just replaced the Mini-USB cable. Can anyone tell me what was the issue here? Do mini-USB cables have varying power rating or grades? What did I miss here? Please help.
Some possible issues:
You might be using a usb extension cable. USB looses power with range.
The power adapter might say 1A, but can be lower then the label says.
Try to disconnect so that both USB ports are available. If you have a usb-wifi dongle or something else that is consuming power, then you can have weird power issues.