My first deal so please be gentle. Thought this was pretty cheap, surely capable at 1080 and 1440p gaming. Reviews on website seem positive. Obviously building this yourself might be cheaper but for those who are not confident then this is better and comes with a 3 year warranty. That GTX 1070 is supposed to be equal to last years Titan X, a card which costs more than the price of this whole PC.
550w Corsair PSU inc.
Does not come with OS but you can either add that as an option (£75) or install yourself.