Yet another "Which Card" newbie question

[Betawave]

I'm very new to this, so please be kind if this is an obvious question.  I've been reading the forums, but I haven't found an answer yet and I think I need input from the experts here.

I want to build a decently powerful rig, dedicated solely to hash cracking and expected to run almost 24x7 until it falls over.

I have up to $4500 to spend on GPUs, but would obviously like to keep costs down if I can. (The rest of the kit..mobo, CPU, RAM, etc. is budgeted separately.)

My local discount PC reseller (in local currency...I'm not in the US), sells various models of the 980Ti ranging between $1493 (water cooled, reference form) and $1149 (triple fan, non-reference).

The 980 is available for as little as $830.

I can get the GTX960 for $343.

I'll be running this in an environmentally controlled room with plenty of air cooling capacity and abundant power.

Unfortunately, I haven't been able to find reliable sources for real world hash cracking performance to calculate which is going to give me the best performance given my GPU budget.

Would I be better off running 3x 980Ti?  5x 980?  or something crazy like 12x 960 with PCI splitters?

The goal is maximum hashes/sec with primarily fast hashes.

Thank you in advance for your advice!

[royce]

FWIW, this is what I did, hardware-wise:
http://roycebits.blogspot.com/2015/08/no...d-air.html

And here are some performance benchmarks for descrypt (but they are useful for judging relative speed). Prices have come down a bit, so adjust your numbers accordingly.
https://gist.github.com/roycewilliams/62...8c8520fe00

GTX 970s are the best for performance/watt/$. 980Ti is better if you have the budget and power. Get the single-fan reference versions if you can.

[royce]

Also note that upcoming 1.38 release of hashcat has *significantly* better descrypt and LM performance, if those are of interest to you.

[rico]

Unfortunately, I haven't been able to find reliable sources for real world hash cracking performance to calculate which is going to give me the best performance given my GPU budget.

Benches:
GTX Titan X, 980 and 970 benches.

GTX 980 Ti

Two second Google search, e.g. - "hashcat GTX 980 benchmark"

[Betawave]

Thanks to all who have replied.

I've run the numbers and based on local pricing levels, it appears I'm better off going with the 970 (which is essentially what Royce said already). I can get eight GTX 970 cards vs 4 GTX 980 vs 3 GTX980 Ti vs 2 Titan X. The Titan X is a beast of a card, but with budget restrictions, my overall rate is better going with more of the cheaper cards. From the data I've been able to gather, there appears to be a significant drop in performance from 970 to 960, so the 970 seems to be the sweet spot (taking all the assumptions that also go along with an 8 card rig). If I'm making a huge mistake, someone please tell me now! :-)