GPU Choices ?

[epixoip]

lets take the NTLM for example, the 290x gives approximately 21 billion tries and the GTX 980 approximately 15 billion, what would the numbers be for multihash ?

Since you specified NTLM, here are some NTLM benchmarks:

Code:

Attack                                  R9 290X         GTX 980
Brute force, 1 hash                     22957.6         21521.5
Brute force, 10k hashes                 11489.4         12101.2
Brute force, 1M hashes                   1986.3          3113.7
rockyou+d3ad0ne, 1 hash                  5676.2          5974.2
rockyou+d3ad0ne, 10k hashes              4443.1          4737.0
rockyou+d3ad0ne, 1M hashes               1872.7          2879.1
rockyou combinator, 1 hash               8913.6          8759.8
rockyou combinator, 10k hashes           7345.0          8426.4
rockyou combinator, 1M hashes            1948.5          2840.7

GTX 980 easily keeps pace with -- and in several cases outperforms -- the 290X, even though it has 768 fewer cores and draws only half the power of the 290X.

like i said i dont care for the power consumption

You should. Power == heat. Heat is difficult to deal with, especially in multi-GPU setups, and especially if you buy OEM-design cards.

its a comparison between perf/price now,that is if i get 2 290x for the price of one 980 for example and i get double or better performance in the 2 290x ill go for 2 290x.

Sure, if money is a factor and you can actually power & cool two GPUs, then go for 2x 290X.