Fret Rattle

I'm tuned to Drop-C have been for a few days now and changed to .11 gauge ernie ball strings.
I've suddenly got a very prominent rattle when I fret the low-E string, be it clean or distorted. If I pluck or strum the string open there is no rattle, can anyone help me figure out where it is and how to stop it?

It is a rattle not a buzz, so I'm sure it's not the action.

your playing a stratocaster right??
even if you are not i guess it does really matter just a strat got a lot going on. first figure where the rattles coming from. more the likely it's going to be the bridge. so fret the string and strum then with your free hand start touching places where the rattle could be when the rattle stops you just touch it and solve from there(examples could be screw lose, string of center, ect). Also if you are playing a strat check that you installed the springs for the added tension right and they aren't doing anything funny.

update cuz i can help you with this over the internet just give more details

rise the saddle on the e string some see if that helps. if not try putting a small peice of paper under the e string at the nut (this is a little getto). You may need to have your nut re-done as well.

Yes its on my strat,
I lowered the bass side of my middle pup (for tonal reasons) and now the rattle isn't there just a bit of fret buzz,
I have the saddle as high as they 'should' go, the screw is flush with the top side of the saddle, tried to screw in the trem claw but it won't go anyfurther cause one of the screws was installed on an angle (louzy manufactors), so the bridge is floating by about 3mil.

so the rattles gone it was the string hitting the pickup?

I think so, or it was picking up the string rattling when against the pick (yeah technique fail haha).

I put some paper in the nut and it's helped with the buzz, so thanks guys.