i'm getting ready to overlay 1/2 inch cdx on my sub floor which is 1x8 planks
i have screwed all the planks to the joists with 2 inch coarse deck screws. This took most of the noise out of the floor however there is still some squeak. Should i be concerned about this? Or will overlaying the cdx take care of that issue?

I get most of the noise when stepping between the joists.

I plan to glue and screw the cdx to the sub floor using 2 inch coarse deck screws and sub floor adhesive.

you could work forever and never rid yourself of 100% of the noise.
Make sure you leave a gap between sheets of plywood, the thickness of a nickel is good.
Wood rubbing against wood is causing the squeaks.

thanks for your feedback this sub floor has been driving me nuts and i'm ready to move on to the next stage.

thanks again
nick

1 x 8 subfloors will always be noisy. The nature of the beast, so to speak. They creak and groan. It should improve somewhat with another layer of plywood and your wood floors on top of that.