I've read all i can on intonation and i've searched threads but none seem to include single note intonation if thats what it's called

Basically i have an Ibanez S520 and the G-string in particular is slightly off on the frets compared to open and on the 12th. My intonation is ok when i play an open G and then the 12th fretted G, but then when i fret second and play the A its sharp enough for me to notice the difference. I have no idea how to solve this but it's making my chords sound terrible!

I'll greatly appreciate any advice or links or whatever!

Thanks guys

Guitar is an even tempered instrument and what you're hearing is the slight compromise that had to be made in it's design. Some people can't hear it or barely notice it so it;s a good sign for your ear that you can. Even a well intonated guitar will not eliminate this. There are special nuts (Buzz Feiten tuning System for eg) that help but they have to be installed by authorized techs and require a special electronic tuner with setting for the offset in order to correct this. I think Yamaha actaully put out a guitar with a compensated fret layout. It looked weird as instead of a straight fret running across the fingerboard there was a little 'bump' in the G string area that was offset from the rest of the strings. Check it out, it might still be on their website!
Moving on.....
I always wondered why the G string always sounded a little out of tune. Even though every thing else was spot on! Thanks Ken for clearing that up for me!
Thanks guys,

I've had another look round google and a few people say that it's just the nature of the guitar. I'm going to try what sugapablo said and perhaps try a different string gauge. At the momment im using 9 - 46 hybrids and i've been thinking about switching to 10's for a few weeks now, i'll see if it makes the difference a little less noticable.

Cheers for the replies

The wound G-String is the cheapest method and it did work for me. Buzz Feiten is an obvious fix as well, but depending on your guitar, you might not want to swap out a stock nut. There's also a company called "Earvana" that makes a CTS (Compensated tuning system) and seems to have on that will fit over top your existing nut, therefore not messing with the "vintage-ness" of your guitar.