"a LCD" or "an LCD". I know about the rule of using "an" only before words that begin with vowels, but for some reason "an LCD" sound more correct.

The right one would be "an LCD". The use of "a" and "an" depend on the sound more than the spelling. For example, we write "a union" rather than "an union" because the "u" there is pronounced as "yu". But if it's used with "umbrella", where the "u" is pronounced as "a", it would be "an umbrella", as we all know. Hope that helps :)

I would use "an" but unfortuanately I'm not very good with grammar! Interesting question though...

you are correct. "An LCD" is the correct usage. The rule isn't using "an" only before words that begin with vowels. The rule is using "an" before words that begin with vowel sounds. LCD phonetically is el-see-dee. The same is for the word "hour." Although it starts with an "H" it is not pronounced when you say the word. Hope this helps!

Because there are words that have a vowel sound, then it is grammatically correct to place "an" before that word. Examples would be "an MBA", "an historic event", or "an honest life".
Therefore, the correct usage of grammar in this case is"an LCD".

When you are saying LCD (as in "el-see-dee), you would say "an" because of the vowel sound when saying the letter L. At least I think so...

An LCD. Because the letter "L" makes a vowel sound when pronouncing it.

And the rule of thumb is for all words which start with a vowel sound, not which start with a vowel. There are some words which begin with a vowel but won't have a vowel sound, so an "a" will be used in those instances. I can't think of any examples right now, though.

An LCD. The rule is that you use "an" before words that begin with a vowel SOUND and "a" for words that begin with a consonant SOUND. So even though L is a consonant, "LCD" begins with a vowel SOUND.