Wednesday, May 23, 2012

Hash Rig v3.0

My Hash Cracking rig v3.0 is now fully operational and running sweetly :)
Here's a pic:
Hash Rig V3.0

The specifications currently are:
  • 1 x Gigabyte 890GXA-UD7 Motherboard
  • 16GB RAM (4x4GB Apacer 1333)
  • 1 TB HDD (Western Digital)
  • 6 x ATI 6950 1GB GPU's (stock clocks, but OC capable)
  • 2 x 1000W PSU (Cougar & Raidmax)
  • 3 Fans, 1 large one positioned between cards 1 and 2 (see below under "Cooling")
  • AMD 3.0ghz 6-core CPU

Current benchmarks I get from MD5 is 28.7 billion/sec through Hashcat-Lite. Obviously other algorithms have differing values.

Hash Rig V2.0 - What Happened?


V2.0 of my rig was an attempt to try and do distributed cracking accross 3 machines. Due to constraints with my hardware availability, I had the following machines:

Machine 1 - 3 6950's, 8GB Corsair RAM, 1TB disk etc.
Machine 2 - 2 x 6950's 8GB Apacer RAM 500GB disk etc
Distributed Hash Rigs. Looks nice, but does is it practical?
Machine 3 - 1 x 6950, 4GB RAM, 80GB disk etc.

Due to not having enough PCI-e slots, I had to forfeit a card for the above setup. Below I have the pro's and cons.


Pro's
  • Relatively "Safe" from burning components, and looks neat.
  • Allows you to run multiple jobs if you are not using distributed cracking.
  • If a particular device fails you can fix it while the other 2 machines are running.
Con's 
  • Much slower than a single rig, even with distribution.
  • Although unix-ninja and Bitweasel have done great jobs on going the distributed route, it is still not as perfected, reliable and tight as going in single-rig mode. 
  • You have to ensure you run everything with the same configuration to avoid confusion. 
  • Can get expensive adding cooling, components etc.
  • Does not run as cool as a rig (about 82C on the hottest card) 
The conclusion for me was finally that I should go back to a rig, even after the disaster from Rig v1.0. As you can see above that has paid-off since the rig is running nicely, speeds are good and i am not losing anything going between distributed and single-rig.  
 

Hash Rig v.1.0 - Barbeque Anyone?


I started off building a rig from scratch. Using the frame below that Panda kindly gave me (he built it) I set off creating a rig.

First steps in rig building
I started off with 3 GPUs (6950) and mounted them on the rig frame. See some tips below;

Tips
  • Put some rubber on the middle bar that the cards "lie" on to prevent them shifting around. Remember only the front of the card is screwed-in so the back is free.
  • Plan which brand of cards  you will buy ! I had 2 MSI's and 2 Club 3D's which fitted in fine, but then I bought 2 Gigabyte 6950's and in GB's wonderful card design, they have the power connectors right up against the end of the card. The problem is on the rig frame, depending how you build it, the power connectors land up being right up against the one side of the frame so you want fit a power cable in. This means getting and angle grinder and lots of annoying work. Rather plan for it and do your homework.
  • Do not buy cheap PCI-e Riser cables! See the pic for an example. These cables are usually sold on Amazon, and eBay and go really cheap, anything from $2.99 - $11.99. They are rubbish. The solder is bad, connections become faulty and things go bad. My recommendation is to spend the extra money and get the excellent products made by Amerirack.
    Example of a cheap & nasty pci-e riser cable!
  • Finally, if you are going to use two power supplies you will need to "bridge" the power switch on the one PSU in order to be able to turn it on and off. To do this follow this useful guide and remember You do this at your own risk!
How to turn an PSU on/off without a mobo.


So you're probably asking, what happened to the Rig v1.0 that you needed to rebuild it?

The short answer : It caught fire! :-)

The long answer: I had an MSI Big Bang Marshal II motherboard with 8 x PCI-e slots which was absolutely awesome. From my investigations it appears that something fell into the PSU power connector on the motherboard (might have been some of the shards from angle grinding in the past), and caused the system to short.

Burning PSU connector fused to Motherboard
Instead of turning off, the connector just burnt itself out and caused a bad smell and lots of smoke.

So, when venturing into this field which can be very rewarding, remember : Be careful, work slowly, get lots of input from experienced users!


Cooling


Cooling an open-air rig is not necessary unless you are in an environment with VERY hot ambient temperature.  However, like I found - some of the CPU's especially AMD's pump a lot of heat out via the heatsink + fan. This rises right into the two GPU's above it and can heat them up. Place a strategically located, and large enough fan, to blow this air out quickly and keep the cards cool. 


The end :-)


You can find me on #haschat on Rizon or #intern0t on Freenode if you have any questions.

Thanks to Atom and the guys from Hashcat from always answering my questions and giving me input, criticism and other niceties :)


-Dimitri AKA Rurapenthe