I have an ibanez grg270 with edge-III tremolo. So i tried to use the "Standard" string height from the ibanez instruction manual, which is 1.5 - 1.7mm for first string and 2.2 - 2.4mm for sixth string. By following this my guitar is impossible to play. When I fret a note, the string will touch the next fret. So it create buzz and hella low sustain. So what is the proper neck relief and string height. I have adjusted the neck but still can't find the sweet spot.

What fret are you measuring this action from?

Assuming you're measuring from the 12th fret, what Ibanez is recommending is higher action than what I'm comfortable with. I'm a lot more comfortable with getting about 1.7mm on the 6th and 1.2mm on the 1st at the 12th fret. If you're getting buzzing even with your action raised up like that, then your neck relief is totally wrong. The symptoms you're giving suggest that the neck is backbowed. How much relief does the neck currently have?

Here's a link on how to measure neck relief, and adjust the truss rod on a guitar if the current setup calls for it.

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I also have to do that. Cottaging this weekend
Action and relief are subjective and changes from person to person.  It also changes depending on how good the fretwork is on your guitar and how worn the fret are.  On an electric guitar a good starting point is 3mm action on the 14th fret at 1mm relief on the 5th fret.  Both those numbers are pretty high and you will probably want the guitar to be set lower, they are just a starting point and should be decreased by lowering the action and tightening the truss rod depending on what you like and what your guitar is capable of.  If you are still getting fret buzz at those high settings then you probably need a fret dressing.

Usually when you are getting buzz on upper frets and not the lower frets it means your truss rod is too tight.
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 Copied this from an Ibanez maintenance pdf.... might help with relief spec's..... of course you would need the tools...

"To  adjust  the  truss  rod,
locate  the  truss  rod  nut  and
adjust it by inserting the
correct  wrench  into  the  nut
and  tightening  (clockwise)  or
loosening (counter clockwise)
the  rod.  Truss  rod  tension
can    be    measured    by
installing  a  capo  at  the  first
fret the holding the strings down at the fret position where the neck joins
the body. Insert a thickness gauge between the string and the fret at the
8th  fret.  There  should  between  0.3mm  to  0.5mm  clearance.  That
clearance is referred to as “neck relief.” Too much neck relief can cause
the  neck  to  have  higher  action  in  the  middle  of  the  neck  causing  poor
intonation  and  uncomfortable  playability.  No  neck  relief  can  cause  fret
I just reread my diagnosis and realized to told you to go the wrong direction with your truss rod.  If upper frets are buzzing your truss rod is loose causing the neck to bow forward and probably needs tightened and your action raised.  I don't know what I was thinking yesterday. 
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Last edited by CorduroyEW at Jun 24, 2017,