SLI 970 vs SLI 980, or other.
I'm working on improving the rig for my office (pen testing and information security consulting)

Im not use what GPU is in use at the moment, i know its r9 200 series but not sure what gpu (im abroad atm so can't check physically).

Anyway, Benchmarking gave me terrible results, for example, NTLMv2 is around 300.
i read around the forums and at first i was going to go for 290x because i saw this:
and many times we need to get NTLMv2 hashes, which according to this, 290x does twice as fast, but then i saw MANY new posts here saying that "newer rigs should use Nvidia" so, did they fix it using drivers?

and assuming ATI is irrelevant, and the fight is between 970 and 980, it seems that 970 is about 2/3 the price, is the performance difference substantial?

cooling is less of an issue since the rig is in our server room.

Thank you.
First, you don't need -- nor do you want -- SLI. The fact that the title mentions SLI shows that you need to do some serious homework.

The 970 has the best perf/$, but if you can spare the extra $, then go with the 980 instead. Just be sure to buy reference design cards, not OEM design cards.
Thank you for commenting, yes i am very new to this - trying to read as much as i can in the forum the learn.
Sorry, when i say SLI i just mean to say "Two cards"
Yes, i need to to homework since im not really 100% sure what "SLI" means - but for all intents and purposes i meant simply "2 cards"

About the "buy a reference card"i read your post here:
and you said, "if there is gaming in the title, it isn't reference"
does it also apply to this (looks 100% identical to Nvidia site):

Thanks again!
Yes, EVGA 06G-P4-4992-KR is a reference design card