I know what you are going through, it is bad !
I have been there my self with Boss pedals.

First up an noise gate wont help as it only cuts out noise between bursts of playing, what you need to do is stop noise from getting in in the first place.

Are you using single coil pickups ?
Do you have fluorescent tube lighting near the guitar ?
Is your computer monitor on when you are playing ?
Have you eliminated any ground loops ?
Are there any other things that could be generating "electronic" noise in the vicinity.

All of these things are easily fixed and if not, then we can have another think.