(02-11-2016, 04:24 AM)epixoip Wrote: Yeah, it looks like most of what you've been researching is bitcoin/litecoin mining stuff from 2011-2013. Which can be helpful, but mining is only analogous to one facet of password cracking: single-hash brute force. This is why miners can get away with ultra-low CPU and RAM requirements. Also there's an economic incentive for miners to do everything on a shoestring budget, as money spent is profit lost. But there's much more than just single hash brute force when cracking passwords, so we need things like CPU and RAM.
Currently the best GPUs for password cracking are from the Nvidia Maxwell family, i.e. GTX 970, 980, 980 Ti, and Titan X. You can go with an older used AMD card if you'd like, but they won't be as fast and they'll draw a lot more power than Nvidia Maxwell cards.
I wouldn't do more than 4 GPUs with only 16 GB of host memory. If that board only supports 16 GB of RAM, then I'd look into getting a different board.
Awesome thanks for the detailed info, I think that was the case I was looking at older forum posts,
the only thing that mislead me was this website: https://blog.netspi.com/gpu-cracking-rebuilding-box/
their build was running 6x R9 290 with an Intel Celeron 2.7Ghz and only 8GB ram.
I think what I will do at the moment is carry on with this motherboard as I picked it up for only £20 I might as well use it as my starter rig and later upgrade when I get my third GPU - will look at also getting an i5 CPU later in the next month or when I come across a decent offer.
I am still a bit confused how their setup managed to run 6x GPU's with 8GB ram and that CPU.
And one last thing, The Nvidia cards you recommended is the reference design still recommended over the OEM?
***EDIT***
I have had a look at power consumptions
Radeon HD 7970 - 195w - 115000 hash/s
GTX 970 - 145w - 150000 hash/s
Although the 970 offers better 'everything' the price is more than double even at second hand they go from £200-£300 and have not come across any reference designs sold at the lower end.
Currently as this is only a project and a test rig nothing too serious I will probably go with the 7970 just to mess about with - once more money comes in ill look at the higher end NVIDIA cards or just build a second more efficient rig (maybe a new frame made out of aluminium)
Current CPU was £22 & RAM was £10.80 so really cheap crap but initially will see if it can get up and running and ill keep my eye open incase I come across any offers, probably upgrade them within the next month or so.
Anyway if anyone is interested I can post progress of the rig.