[MHordecki]

What is the grammar rule?

I've always assumed that you use "an" whenever a noun starts with a vowel sound, which "Nvidia" does ("n" being pronounced as "en"), thus making "an Nvidia" the grammatically correct one.

[foobiekr]

This is actually a deeper issue about the confusion between the language itself (english phonology requires what you're describing) and the written form. No english speaker in the world, unexposed to the written form of "Nvidia" would ever say "A Nvidia."

[IshKebab]

The rule is just "which one is easier to say? use that one". "A nvidia" is just wrong.

[sangnoir]

That entirely depends on how you pronounce "nvidia" in your head. I can imagine someone who has never heard the name spoken out loud think of it as "ni-vidia" (I have done worse) and "a Nividia" is easier than "an Nividia"

[IshKebab]

I mean, that's just pronouncing it wrong.

[sangnoir]

You are right: my point is that the easy way to say something can very well be the wrong way to say it.

[IshKebab]

I meant is it easier to say "a nvidia" or "an Nvidia", assuming you are pronouncing nVidia correctly.