The sharp-eyed reader may observe that I have sometimes used an alternate spelling for the word commonly spelled as "nerd." In fact, before the movie Revenge of the Nerds, the only way I'd seen it spelled was knurd, and nurd.
A little web research says that I am part of a minority opinion that holds that knurd was a coinage at RPI, derived from "drunk" spelled backwards (a trope later used by Terry Pratchett). Certainly "knurd" was the first spelling I saw, in the RPI Bachelor college humor magazine, in 1968. The earliest appearance of the alternate spelling that is noted on the amateur scholarship sites that I can find is "nurd" in a 1965 issue of the Bachelor, which I have seen, and even probably have in some file boxes somewhere. When I was a publications knurd at RPI, I scored back issues of many of the student publications and I was fascinated.
The predominance of the k and u spellings of knurd at RPI is a fact. The question is whether or not the word itself under its current meaning (someone consumed with intellectual activities, often having poor social skills), came from RPI. There is, incidentally, no real argument as to the first appearance of the written word "nerd." That was in a Dr. Seuss book in 1950, and the word was cited in a Newsweek story in 1951 as being someone who was "square," which is close enough to the modern meaning. But the Newsweek reportage was translating oral slang, so the spelling gives no real help. The Dr. Seuss coinage may have been the source of the spelling (the meaning in the Seuss book was ambiguous), while the oral usage could have been inspired by the knurd/drunk origin.
Still, there was an earlier humor magazine at RPI, The Pup (famously banned for having published a fake and very unflattering picture of the dean of students). The issues of that magazine that I read didn't include a usage of knurd, to the best of my recollection. I've spoken to RPI alumni from earlier times, but, unfortunately, people in general do not have the sort of memory segmentation that I have, so they haven't been of much assistance.
The most parsimonious (and therefore most likely) explanation is that the origins of the word are still unknown, but the knurd spelling of it came from a later surmise by some students at RPI. I will hold out one not unreasonable possibility: the postwar GI Bill period of American colleges was a time of massive expansion and flux. It's not at all impossible that the origin of the word was indeed "drunk spelled backwards" and that this origin was first lost, then later rediscovered by the same sorts of students who'd invented the word in the first place. Certainly the Pratchett example is one of parallel formation.
It's not as if knurd isn't a natural category, after all. We self-select, and self-identify. If we don't, others do it for us.