(02-11-2016, 02:55 AM)zozeri Wrote: CPU: Intel Celeron G1840 Processor 2.8 GHz
RAM: Kingston 4 GB 1600 MHz DDR3

(02-11-2016, 02:55 AM)zozeri Wrote: GPU: None purchased - either 7970 or 290x

(02-11-2016, 02:55 AM)zozeri Wrote: 4) OS - I want to use the rig as a remote server that I can use via command line.

Quote:... So, are you building a password cracking rig, or a bitcoin miner?  If you plan to run six GPUs with 4GB VRAM each, then you should have at least 24GB of host RAM. There's certainly no reason to skimp on the CPU, either. You don't have to go with a i7-4790K, but you should at least go with an i5-4590 or something.

Quote:Why those GPUs? There's usually never a good reason to use AMD GPUs in a new build. I guess it's because you're wanting to spend no more than 100 GBP per GPU? Keep in mind those GPUs are power hungry pigs, you should budget for them pulling 325-350W each. This means on your 1200W PSU you should only power three GPUs max. Any more than that, and your nice wooden chassis will turn into a pile of ashes.

Quote:Linux is the obvious choice.

Quote:CPU/RAM/Hard Drive
All of these can be generic. It doesn’t hurt to max these out, but they don't really impact cracking performance. If you’re going to throw money around, throw it at your cards.

Their rig specs;
Component Model Est. Price
Case 6 GPU Rackmount Server Case $495
Motherboard: ASRock Motherboard H81 PRO BTC $64
Risers (6): PCI-E 1X To 16X USB 3.0 Riser Card $24
GPUs (6): XFX Black Edition R9 290 $1,884
Power Supply (2): CORSAIR AX1200i 1200W $618
Power-Splitter: Dual PSU Adapter Cable $9
RAM 8 GB: - Any Brand $50
CPU: Intel Celeron G1820 Dual-Core (2.7GHz) $45
HDD: 1 TB - Any Brand $50
Total $3,239

(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.

(02-11-2016, 04:33 AM)zozeri Wrote: 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.

(02-11-2016, 02:56 PM)Flomac Wrote:

(02-11-2016, 04:33 AM)zozeri Wrote: 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.

Karl from NetSPI obviously doesn't know what he's talking about. Ask him for a real world hashcat job instead of posting simple benchmarks. There are many ways to do hash cracking and a 2.7GHz Dual-Core feeding six GPUs is limiting you from most of them.

On top he's dealing with a lot of heat from the six 290x as he writes in his blog, well why not using reference cards as it is claimed here since years? And put at least some fans in the case. Then your benchmark might stop showing lousy 10.4 GH/s in MD5 - almost 10% under the expected value.

So again, that blog is at no point a good advice for building a rig.

(02-11-2016, 08:55 PM)epixoip Wrote: You're cracking a small list of unsalted hashes. Try cracking a larger set of salted hashes, and you'll see why CPU & RAM matter.

(02-11-2016, 09:01 PM)globus Wrote:

(02-11-2016, 08:55 PM)epixoip Wrote: You're cracking a small list of unsalted hashes. Try cracking a larger set of salted hashes, and you'll see why CPU & RAM matter.

That's fair. The bulk of what we're seeing is MD5, NTLM, and NetNTLMv2. I'd love to see the NetNTLMv2 hashes go up in speed, but most of these are coming from domain users, so it's not hard to crack Winter2016.