IAS makes BiS?

[wicked night]

So I'm currently playing with a one-hander and shield; Not the best damage but it's steady enough.
My main-hand is an axe with 15% IAS (1.5 attacks/sec), nothing too fancy.

The other day something caught my eye:
A plain 15% IAS ring had a 500 dps increase over another with 114 str and 9-18 dmg.
So I got another, for a total of 1.94 attacks/sec.

My first thought was "I must be doing something wrong" since everyone else values every other stat over IAS, and yet the damage calculator is telling me this is a clear damage increase.
It does make sense in my head as well (more attacks/sec equals more damage), but these are the main 2 damage stats we're talking.

What am I missing?

[hubb]

IAS stacks multiplicatively, so 15% IAS is a direct 15% increase in DPS. Whereas the damage and strenth is additive with your already high base damage and strenth, so their relative contributions are much lower.

500 DPS / 1.5 APS = 333.3 per hit
9-18 damage is an average increase of (9+18)/2 = 13.5
(333.3 + 13.5) * 1.5 APS = 520.25 DPS

500 DPS * 1.15 = 575
OR (just to show it's the same thing)
333.3 per hit * 1.5 * 1.15 = 575
333.3 per hit * 1.725 APS = 575

Don't know your strength so I can't do that calc, but it comes down to the same thing

[wicked night]

It seems the damage formula is a little more complex than I anticipated; guess I should have a look at it before attempting to upgrade these IAS rings.
Thanks for the tip!

[Kblavkalash]

Just get ring with both IAS and strength/vita, they are quite cheap nowadays.

[gakky]

ditto IAS on Amulets and gloves, 15% on all 4 gives +75% DPS.
I think some uniques like Andariels Visage give IAS too.

[imthedan]

While IAS gives you damage increase, a str ring will give you damage and armor...

is the damage from IAS worth it? seriously question, because I haven't touched any IAS gear... maybe it would help me.

[gakky]

More IAS will trigger hit effects more often. Faster Fury generation, faster Frenzy ramp up, more life per hit, more stun etc.

[editted out mistaken analysis]

I've been testing adding lots of IAS. It does not multiply !! So 2 rings with 15IAS each is just 30IAS. It has the same diminishing returns as strength.
I had assumed it would multiply because Weapons Master gives +10%IAS for polearms/spears. That is totally useless just for DPS ! With 100IAS elsewhere it's only +5% damage. Swords and daggers though the 15% damage is always multiplied.

[Warrax]

Just get ring with both IAS and strength/vita, they are quite cheap nowadays.

Maybe you got lucky but even blue rings of that kind are pretty expensive.

[gakky]

some more testing results :
IAS on weapon is treated separately and does multiply other sources. Off weapon and skill IAS seems to added together.
DPS = damage * (1 + weapon IAS) * (1 + off weapon IAS + skill IAS)