Ok, don't take this the wrong way, but Your spec is bad. I have an arcane mage with a similar GS to yours, and I pull between 7.5-8.5k dps on ICC10 bosses including Rotface and Festergut (and yes, I do my job and don't just stand there nuking or it would be higher), and I'm still not happy with that. I'm going to come off as rather mean in this post, but take it with a grain of salt. It's mean because it's going to end up being so long because I'm going to explain your errors and how to fix them in detail, and WHY, instead of just saying "use this spec and you'll be l33t".
You've gone far too deep into the Fire tree, taking abilities that don't help your arcane spec in any way whatsoever. Arcane Mage DPS is based off single target damage, not aoe's from fire or any fire spells whatsoever. Lose the points you have in ignite, impact, and improved fire blast (since none of those should be in your rotation as arcane anyway) and keep your 3/3 incineration because it gives your arcane blast 6% more crit chance.
As for your arcane tree, another set of bad choices. Arcane Mages are focused on SP & Haste. You skip some of the basic haste abiltiies and take others that are of 0 use to you since you should be using your Molten Armor anyway.
Your spec & glyphs should look like this: http://www.wowhead.com/?talent#of0Vs...cZbhf0o:Nzi0mV and if you do any runs in ICC it should look like this: http://www.wowhead.com/?talent#of0Vc...cZbhf0o:Nzi0mV (until 3.3.3 comes out, then skip it)
I'll proceed to explain why.
Arcane Fortitude - great for pvp, crap for pve. If you are doing your job right as a DPS, you aren't taking damage in a raid, or if you are, it's not enough to bother with this ability. Doesn't help you in any way. You have 3/3.
Arcane Stability - this talent is kinda optional. Again, in these raids pushback and damage interruption should be minimal, and you can avoid some damage interruption by popping Icy Veins (discussed later)
Magic Attunement - This talent is also optional. I use it in one of the specs, but what it gives you in utility point for point with stuff from the rest of the Arcane and Frost trees far outdoes any benefit you gain from putting it at 2/2.
Improved Counterspell - again, great for pvp, fail for pve. You just worry about stopping spells in mid-cast. Let priests silence the mobs that can be. Bosses are immune to silence (but not always the interrupt) so this is a waste of 2 points for you.
Improved Blink - worthless for pve. Not even sure why you thought about it. General rule for pve DPS - "if this doesn't improve my damage or my ability to deal damage more efficiently, why would I take it?" It's great for BG's, total fail for Raids.
Prismatic Cloak - fail for pve. Again, damage absorbtion is not your concern, DPS is. You aren't a tank. Another PvP talent you wasted 3 points in.
Now for the things you need to take and why:
2/2 Arcane Subtlety - Reduces Threat. You don't necessarily need this, but I draw threat with 2/2 and a pally tank dropping 9k TPS, so I advise it.
3/3 Arcane Focus - You don't have enough hit @ 260 to be hit capped for bosses. This effects your DPS directly. If you ever see "miss", you fail. Sadly, arcane mages only need 210 hit if they take 3/3 arcane focus and 3/3 precision (in frost), making room for craploads of SP and Haste which directly effects your dps. Also, Arcane is extremely mana intensive as a spec for bossfights (if done correctly) and you will run OOM even with all the abilities that reduce mana usage taken. This is not optional.
1-3/3 Student of the Mind - if you are using the T9 2pc set bonus (which you are), this increases your crit chance as well as your mana regen. Mana regen is awesome, but avoid MP5 on items like the plague.
3/3 Arcane Meditation - mana regen while casting is HUGE. Not optional.
5/5 Arcane Mind - increases your mana pool and crit chance. Not optional.
0-3/3 Incanters absorption - optional based on the bossfight, increases your spell power based on the damage you absorb, so pop your frost ward on Marrowgar and stand in the coldflame for a few seconds to spike your dps by a couple hundred points. Not needed for all fights, and is getting nerfed in 3.3.3 into uselessness.
3/3 Netherwind Presence - increases your HASTE. Not optional. Point for point haste>crit for arcane mages.
3/3 Ice Floes - reduces the cooldown of your Icy Veins. Self explanatory.
2/3 Frostbite - fills space, not completely useless, but needs to be taken to move to the next step on the tree
2/2 Frost Warding - extra spell absorbtion and potential mana regen. Not bad.
3/3 Precision - less mana use and 3% extra hit. That's huge. Also takes you to that 210 hit to reach cap to hit bosses.
1/1 Icy Veins - self explanatory, I hope.
Make a macro that combines your Arcane Power and icy Veins in one keystroke and you have your own personal mini-heroism/bloodlust.
Also, macro in your nevermelting ice crystal with your talisman of resurgence and your arcane blast. This maximizes your spellpower and crit boost uptime and makes sure you never miss the opportunity to use it.
Glyphs - Arcane Blast, Arcane Missiles, Molten Armor. End of story. Not Optional.
Gearing - Get your 4pc T9 using head, shoulders, pants, and gloves. The extra it gives you outweighs anything you get from the 245 head & shoulders. Run VoA 10 & 25 every week and try to get your t10 pants & gloves to drop. Don’t buy them with frost badges, only buy your head & shoulders. For the chest, get a Merlins Robe made, and for your wrists get Bejeweled Wizards Bracers made. Later trade your merlins robe in for a meteor chaser’s raiment
For your weapon, lose the 81 spellpower and get a Black Magic enchant. I’d try for the 264 Frozen Bonespike (with Black Magic) off Marrowgar and then the Shriveled Heart for HHoR final boss (rawr shows higher dps than 264 Nibelung.)
Gem for Spellpower in any slot you can, and spellpower/haste in yellows as long as it gives you more than 5 spellpower for the socket bonus. Any less, go 23 spellpower regardless. If you gem blues, use 12 SP 10 SPI to activate your meta.
When choosing gear, focus on items with Spellpower, Haste, and Crit. Skip them if they are just spellpower/crit unless it’s a huge upgrade for you.
You also need to use a belt buckle on your belt to add a socket, and you need to enchant your Bracers, your chest and your Boots. Boots go with Tuskarr’s Vitality (increases movement & adds huge survivability) and bracers use spellpower, chest go 10 all stats. Try to hit 3k SP and at least 700 haste as a starting point. Replace your nevermelting ice crystal with the Abyssal Rune if you get the chance. Lower gearscore, but higher DPS overall. (same happens with offhand. Shriveled Heart > Scourgelords Baton in both 251 and 264 forms, and the heart is only 232 Ilvl)
I think that’s it. ABx4 or until it procs Arcane Barrage, then fire arcane missiles, rinse & repeat. Toss your AP/IV macro in for mini-heroism, and your trink macros into your Arcane Blast will increase base DPS by a ton. Also, make liberal use of Flasks of the Frost Wyrm, 46 Spellpower food (either fish feast or tender shoveltusk steak) and crazy alchemist potions & mana gems in a cycle to maintain your mana pool. If you have any questions, let me know.