An interest in geeky things in and of itself is not diagnostic of Aspergers. What matters more is if you have trouble with interpersonal relationships, which I definitely did growing up. Things are much better nowadays, but it took a lot of hard work to get from A to B.

Deep interest about any topic which is considered "uninteresting" or "impractical" by "normal" people. Might be the history of a particular aircraft, or a car, or an event in the distant past. Your brain is consumed by it for completely irrational reasons and you feel obliged to dig even deeper.

One thing that I'd say makes it more specifically an 'aspie' thing is that it's often obsessive to the unhealthy point of severely neglecting other aspects of life, and it can be weirdly temporary. Something like being into sudoku's for weeks on end, and then entirely forgetting about it afterwards.