Any where the male and female leads are both nerds? They start to fall for each other. Some other guy who isn't nerdy comes in between them. Maybe she becomes less of a nerd because of the other guy, but then goes back to being nerdy like the male lead. Maybe the other guy succeeds in getting her at first, but in the end she realizes her love for the male lead. School or adulthood acceptable.
Healer - I'd say the leads are nerds in the sense that they're quirky and kind of loners (i.e. not nerds in the genius / book-smart sense). The leads are very close as kids but get separated, when they meet again they don't recognize each other and the FL has a crush on a non-quirky guy, but the ML and FL quickly develop feelings for each other (with some dual identity complications - lots of fun) and do get together.
Sungkyunkwan Scandal - the leads are both huge book-smart nerds. It's basically the reason they meet. There is a great second male lead who is, let's say, more athletic than them, but still nerdy in his own way.
Love O2O - the leads are both smart and capable computer science majors. Might not be exactly the dynamic you're looking for because they're also considered the university's best looking guy and second best looking girl and the other criteria you mentioned aren't there, but I'd still recommend checking it out.
Age of youth season 1- the character eun jae and her pair. They both were definitely nerds but it doesnt have the story that u look for. But both were nerds (he may appear a lil witty in the beginning but as times goes by u can see that they are both nerds..btw she is a lil bigger nerd than him.. Lol