to make a long story short me and my guild have been smashing our heads against noth for so much time that we actually start having nightmares about him.
we think we have the right strategy, and on our best tries we brought him at 13% or 14% and a few times around that percentage.
now, i really don't understand what's our problem:

° wrong strategy
° execution
° just a matter of numbers and consumables

so here it is: our RDPS is pretty much always between 5k 5.2k , depending on raid composition (we don't stack, and we aim at repeatability of our kill). Is this actually enough or we need more?

( i take it that if it should be enough we'll work either on strategy or on execution)

Which guild? And yes, more information if you want any help.

1. I dont think DPS should be much of a problem on Noth. Our first kill we had 30 secs left, and last time (2nd kill) we had over a minute to spare. With mostly the same raid, we only had 20 secs left until Patchwerks enrage.

Is all your DPS focusing on Noth for the last phase? Are a lot of them dying? Is the blink being handled well? (This can make a fairly large difference, since DPS can only continue once he is back on the tank)

our % progressions on every teleport are around these numbers: 80% - 65% - 35% - 13% - wipe
we control the adds (we kill them mostly by using dots) and we do DPS on Noth everytime until it's 5s left for blink to be ready.

guild is Ravenous from Dunemaul EU www.ravenoushorde.ath.cx =)

edit: i think blink is being handled quite good, with a hunter always shooting him with distracting shot after a blink thus making him run towards a corner , so the tank has time to go and grab him before he goes for other players

PS: time to edit my profile

If you're DPSing out completely when he's due to blink you're going to be hurting. Sometimes he waits up to ten seconds longer to blink -- you're saying you don't DPS him during that time? I'd recommend minimizing the number of warlocks and firemages on Noth -- put them more on the adds. Hunters can feign and frost mages can ice block if they get aggro on a blink. Have a spare warrior with full rage going into a blink so two people are trying to grab him. Trust your tanks to pick him up ASAP.

Also, are you offtanking adds during his third downtime? You should.

Aim for something closer to 55% by his second teleport, then offtank the skeletons (assign an extra healer to each corner so the warriors don't die) and burn him down.

Edit: Oh, you're Horde? Drop Searing Totems directly underneath Noth at all times. Trust me. :)

we do all those 3 things

Its simply impossible to only shave of 30% during the third downtime. Nooo way. What the hell is everyone doing??

by reading your answers it seems we focus too much on the adds hmmm

The strategy I found worked the best was to put 3 warlocks on dps for adds when Noth is on the floor and nobody else. Their instructions were to just keep Corr, CoA and maybe immolate on all the adds at all times. Our ranged DPS stopped hitting noth at the 5sec blink warning and if they had mana or whatever popped a few fireballs or multishots into adds, but otherwise they were all on Noth. Melee of course never lets up dps on Noth - they go right up to the blink.

During the balcony phase we just assisted the corner tanks to clear the remaining adds and shackle/tank assist trained down all the spawned mobs. Second balcony obviously get the Guardians dead first, then do the same thing with the rest.

The basic idea is, your corner tanks are quite capable of tanking 3 mobs simultaneously, so you trade off dps time on the adds to the balcony phases to buy more dps time on Noth. When we focussed on actually keeping the adds killed all the time, I found our raid standing around during the balcony phase waiting for spawns - which is simply wasted time that you can buy for Noth dps if you set things up properly.

Anyway, your raid might be suited for a different strategy - this is what I found worked for the group I was with.

Edit: one relevant detail - our MT (me) tanked Noth right in the middle of the room. I found that 20 people were getting cursed no matter where we put him, so the middle position was superior because all the ranged dps were always in range of a corner spawn spot *and* Noth simultaneously. Same goes for decursers and healers. Just a minor optimization - the conventional strategy is to tank Noth way over in the far corner which I found to be significantly less optimal.

What is you raid makeup for Noth? We normally have 6 rogues / 3 Hunters / 2 DPS Warriors on Noth with 3 casters (mages/warlocks) per corner on the adds. We use our MT Warrior and a Feral Druid to tank Noth because Feral Charge is sexy in this fight. After balcony 2 we have all dps on Noth with the tanks offtanking the adds with stoneshield pots at the 2 min mark and one priest per.

We use 3 Ranged, 1 Tank, 1 Priest per corner. 2 Tanks on Noth, we hold him in the SE corner. Warlocks pretty much DoT everything that spawns (CoA/CoS/CoE + Corruption depending on corner)
During the first teleport, the OT moves to the NW corner (nearest the entrance) to Stun the 2nd Champion in that corner and help tank (priest shackles it after the stun).
On 2nd teleport, OT goes to NW corner and MT goes to NE corner to stun/tank the guardians. Everyone focus's on the guardians first, and priests shackle Champions. Once Guardians are dead, move to Champions.
After this, everyone except the corner tanks and their healers focus's on Noth. It's fairly common for us to go 80%-55%-0%

Small tricks: As Gurg said, searing totems help a lot. If you're using the totems, encourage your DPS to attack for longer and just watch for the Blink - He will sometimes kill people, it's a waste of DPS if you stop too early just have your druids ready to Rez and get your tanks to react quicker to the Blink (make sure your priests are dispelling the cripple).

The entire Plague wing is very light on Healing required, you really only need 10 "healers" for Noth and Heigan, and having a few healers with hybrid gear and/or spec will help you more than they'll hurt. I say hybrids instead of more DPS classes because the extra dispelling, totems, and rebirth really make up the difference here. I DPS for the first and second downtime on Noth (innervate early and usually have to rez a rogue/fury war) then switch to helping heal a corner tank and Innervate a priest during the 3rd part.