Fully upgraded to newest MacOS: Sierra
2.7 GHz Intel Core i7
4GB DDR3 Ram
Already switched to a 250GB SSD for faster performance
Disclaimer: because the previous battery was defected and only last for an hour, I've requested apple to remove it. And because it would cost money to get a replacement battery as I was out of warranty, I haven't got a battery installed inside the computer, so in order to use it, it has to always be plugged into a power source.