Comment by SilasX

I avoid making exceptions to the rule, but in the vernacular, people definitely break from it! You'll see e.g. "an historic event", usually justified because the first syllable is weak and close enough to being vowel-started.

FWIW "an Nvida employee" sounds better than me an "a Nvidia employee" because the latter has two vowels with no consonant separating them ... and I don't get repetition there because the vowels are different.