Most people aren't interested in one thing alone. You are a good example: you like tech stuff and lifestyle stuff. A blog combining both would be perfect for you, apparently.
But what about the people who like tech stuff and sports, but dislike lifestyle stuff? Or the people who like lifestyle stuff and fashion, but dislike tech stuff? They might come to your blog because of a link to an article, browse your posts, and get turned off by half of them. They will find another blog that fits them better. If your blog were about only half of their interests, it would still fit them better.
And what about people like you? I can only speak of my own experience. I do like different things, but I ususally focus on one of my interests at one time. When I like to involve myself in, say, drawing, I prefer to read about that and not be distracted by input and ideas about the other things that I enjoy. I want to learn how to draw better, generate ideas, and that needs focus and concentration, and thinking about, say, cooking or gardening at the same time will make reading about drawing less helpful and less intense an experience.
Personally, I prefer to decide for myself what I focus on at a given time. If I read about one thing and then think that I want to turn to something else, I will turn to something else. I dislike thinking about one thing and then being forced to deal with something else.
So it all come down to the question: What does one of your blog have to do with the other? If the life hacks seamlessly integrate into the tech theme – e.g. all of your posts in both blogs deal with how to live as and be a good programmer – then they combine easily and will provide an integrated experience. But if they sand side by side and have little or nothing to do with each other except that one may be interested in both, then I would keep them separate so as not to confuse or disinterest readers.