With only 302 haste rating under full haste effects you have 1.06 sec casts for AB and MBAM without berserking, so I'd suggest only using two of icy veins, berserking or speed pot at a time when you have bloodlust up.
2.5 / 1.06 / 1.05 / 1.03 / 1.3 / 1.2 / (1 + (302 + 250 + 500) / 3279) = 1.06

In fact you'd need --- passive haste before you have to start worrying about the gcd cap.
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Edit: fixed

You're forgetting the bonuses with the T10/2pc which grants you 12% haste for 5 seconds and procs approximately every 10-12 seconds for a raid-geared arcane mage (an effective +5% haste) as well as the Netherwind Presence which grants an additional 6% haste. Additionally, Shiatans is a troll mage and is therefore also calculating the haste values with berserking.

Therefore Without Berserking:

(2.5 / 1.06 / 1.03 / 1.05 / 1.3 / 1.2 / 1.12 - 1) * 3279 - 250 - 500 = 63.66 (64 haste to GCD cap)

Edit: i guess the "effective" haste for the T10/2pc wouldn't really be significant to determining GCD caps so I used 1.12 instead of 1.05

Make a macro that swaps out your weapon with Black magic for a weapon with 63 SP on it that way you wont hit GCD

Has anyone else noticed a loss in DPS as arcane since 3.3 came out?
My starts at 2545 Sp 30.1% crit 459 haste and 312hit and a 56/3/12 spec...I seem to have lost almost 1,000 points of dps...Am I the only one to experience this?

delete please

With Scorchio no longer tracking Missile Barrage I did notice a drop off of DPS for a little while at the start of 3.3, however it picked back up again to normal levels once I got used to the new addon trackers I use now. It's possible you could be overspamming Arcane Blast without noticing MBarr procs and evocating more often.

There's no 1000dps loss from any change in mechanics. However, 1000dps is approximately the amount of damage that you would gain from CoE/E&M/EP. Have you checked your combat logs to see if this is being applied?

I don't know if you mean to say that 312 hit is above or below where you want to be as arcane, though neither of those judgments would be accurate. The soft cap for arcane can be insanely low. 3% from the frost talent, 3% from the arcane talent and 3% from raid utility (misery, imp. FF), bring the hit cap down to 8%. If you're alliance and you're a draenei or have one in your group, you can bring it to 7%. At 26.23 hit rating per 1% at level 80, that's 210 and 184 hit rating respectively.

From there you can just start taking points out of hit talents to make up for the the abundance of it on gear. 312 isn't that bad at all, and I've seen mages with even more than that do a hell of a lot of DPS.

A good starting point without using 277 loot will be to pickup 4/5 Bloodmage set with the crafted tailoring pants. Then spend some frost badges on the haste belt and fill in the rest using rawr.

The first thing you need to be striving for is our 2 piece T10 because it is just so ridiculously strong. The fastest way to get this is to get shoulders + gloves for 60 badges each. It is generally agreed however that our T10 gloves are the worst itemized piece, and our chest is the worst for T9 content, so I would advise waiting the extra week or less to get the T10 chest as your second piece. It also depends on what 258 T9 you managed to get.

What? The way blizzard works out damage in AoE with more targets then the damage cap (now 10 targets) is exactly the same except now the cap is considerably larger (the damage you'd do to 10 targets rather then the old fixed caps), unless I'm gravely mistaken in no way should you have nerfed dps against Onyxian whelps.

As for Blizzard vs AE, as any other spec you should be [FS + Blizzard] but for Arcane it's going to be tight and depend largely on what your haste is at as blizzard will gain much larger bonus's from haste.

With ~3000 spellpower, 60% Crit (~700 rating) and 36% haste (~800 rating) (in raid)

Blizzard hit avg = 886 | Blizzard crit avg = 1612 | Blizzard avg = 0.4 * 886 + 0.6 * 1612 = 1321.6
Blizzard avg dps = 1321.6 / (1 (tick per second unhasted) / (1 + 800 (haste rating) / 32.79 (haste per %) / 100) / 1.05 (wrath) / 1.03 (pally buff) / 1.06 (Netherwind)) = 1884.71dps

AE hit avg = 1335 | AE crit avg = 2475 | AE avg = 0.4 * 1335 + 0.6 * 2475 = 2019
AE avg dps = 2019 / (1.5 (GCD unhasted) / (1 + 800 (haste rating) / 32.79 (haste per %) / 100) / 1.05 (wrath) / 1.03 (pally buff) / 1.06 (Netherwind)) = 1919.5dps

Against multiple targets:

Blizzard = 1884.7 * 10 / number of targets = 188847dps / number of targets
Arcane Explosion = 1919.5 * 10 / number of targets = 19195dps / number of targets

It would seem that with the stats I mentioned AE is slightly better than blizzard. Blizzard however increases its dps faster then AE as you gear up due to haste. Either way however if you include error bars in my working, differences in gearing and RNG i would say they would end up about the same.

I did my calculations using a hand calculator so I imagine they're quite rough and someone probably could do a better job with a spreadsheet. It would also depend largely on other spirit, int, setbonus's etc which I haven't factored in, I just used easy numbers to make the maths simple.