Build with two Nvidia RTX 3090

[Mango101Mata]

Hey everyone,

I am currently sitting on two RTX 3090 Flounders edition and looking to build a cracking rig.  I have been scouring the web to help guide me with a build but everything I find is outdated.  A buddy of mine who is really good with building pc's kind of shooed me away from buying a barebone server because he thinks its overkill.  I kind of agree seeing that all of the barebones servers I found that could hold at least two GPU's had a stupid amount of hot swappable bays etc.  I have been looking at the Intel Core i9 X series Extreme edition CPU but I am not sure if that will be enough. Any thoughts?  Budget isn't really a concern but we would like to use the two 3090's since we already have them. We would probably attempt to crack about 1800 passwords every three months or so if that helps.

[slyexe]

Dependent on the type of hashes you're attempting will determine whether or not it is gpu resistant or cpu resistant. So knowing which type of hashes would easily define if you need a GPU even at all. 

Otherwise, the rule of thumb for hash cracking is typically Mainboard RAM = VRAM so if you're using 2x 3090's it would be wise to include atleast 48GB of RAM seeing as each 3090 has 24GB VRAM. As for a guide in the rest of the departments, it's totally based on user. If you're having alot of success and not looking to expand with what you currently have, then a simple basic motherboard would do. Make sure the positioning of the 2x 3090s would be using both 16x PCI-E lanes otherwise you will/could see bottlenecking. We would need more information to determine what's best suited for your setup. 

Hashtype
Room for expansion or not
Budget (which doesnt look like an issue to you)
Experience also comes into play

[drsnooker]

Fascinating! I guess I've never looked at a hash that was CPU bound.... Slyexe: can you clarify which hashes rely more on the CPU? (not to derail this thread too much) May be a a column in the wiki (with the example hashes to specify CPU/GPU?)

[slyexe]

CUDA API (CUDA 11.5)
====================
* Device #1: NVIDIA GeForce RTX 3090, 23336/24575 MB, 82MCU
* Device #2: NVIDIA GeForce RTX 3090, 23336/24575 MB, 82MCU

OpenCL API (OpenCL 3.0 CUDA 11.5.125) - Platform #1 [NVIDIA Corporation]
========================================================================
* Device #3: NVIDIA GeForce RTX 3090, skipped
* Device #4: NVIDIA GeForce RTX 3090, skipped

OpenCL API (OpenCL 3.0 WINDOWS) - Platform #2 [Intel(R) Corporation]
====================================================================
* Device #5: 11th Gen Intel(R) Core(TM) i5-11400 @ 2.60GHz, 24471/49007 MB (6125 MB allocatable), 12MCU

Benchmark relevant options:
===========================
* --opencl-device-types=1,2
* --optimized-kernel-enable

----------------------------------------------------------------
* Hash-Mode 15700 (Ethereum Wallet, SCRYPT) [Iterations: 262144]
----------------------------------------------------------------

Speed.#1.........:        0 H/s (111.51ms) @ Accel:82 Loops:1024 Thr:4 Vec:1
Speed.#2.........:        0 H/s (14647.29ms) @ Accel:82 Loops:1024 Thr:4 Vec:1
Speed.#5.........:        8 H/s (2.35ms) @ Accel:12 Loops:1024 Thr:1 Vec:1
Speed.#*.........:        8 H/s

Started: Mon Jan 03 18:10:23 2022
Stopped: Mon Jan 03 18:11:59 2022


Heres an example of an Ethereum Wallet which would be subject to cpu cracking. Both 3090's result in 0H/S However the CPU will provide 8. There are several others but this is just an example where a $2000 GPU would be irrelevant over a $250 CPU.

[drsnooker]

Ah, yeah never touched crypto, but at 8 H/s you better have a small list of possibilities! Brute forcing is out of the question....
Considering OP is doing 600 passwords a month that's probably not it. I guess we better let Mango speak up with the type of hash.

[Mango101Mata]

Ah, yeah never touched crypto, but at 8 H/s you better have a small list of possibilities! Brute forcing is out of the question....
Considering OP is doing 600 passwords a month that's probably not it. I guess we better let Mango speak up with the type of hash.

Thanks for the quick responses!  NTLM will be the hash. My biggest concern was buying a motherboard that can only hold two 3090's and come to find out I need more GPU'S!  I do plan on storing this build in our server room for better cooling purposes.

[Mango101Mata]

Dependent on the type of hashes you're attempting will determine whether or not it is gpu resistant or cpu resistant. So knowing which type of hashes would easily define if you need a GPU even at all. 

Otherwise, the rule of thumb for hash cracking is typically Mainboard RAM = VRAM so if you're using 2x 3090's it would be wise to include atleast 48GB of RAM seeing as each 3090 has 24GB VRAM. As for a guide in the rest of the departments, it's totally based on user. If you're having alot of success and not looking to expand with what you currently have, then a simple basic motherboard would do. Make sure the positioning of the 2x 3090s would be using both 16x PCI-E lanes otherwise you will/could see bottlenecking. We would need more information to determine what's best suited for your setup. 

Hashtype
Room for expansion or not
Budget (which doesnt look like an issue to you)
Experience also comes into play

Hey slyexe.

Sorry for the late response.  The hashtype is NTLM and ideally I would want room for expansion incase two are not enough.  Budget isn't really an issue but we would prefer to keep the current GPU's we already have.  I don't have any real experience cracking hashes.  I was able to dump the hashes from our DC and tried using a VM running hashcat but it wasn't cutting it.

[Mango101Mata]

Someone mentioned to me that there are thermal restrictions on the 3090's and I wouldn't be able to use more than one of them. Slyxe I see you were using two RTX 3090's. Could you give me some insight as to what your build looks like?

[drsnooker]

1800 passwords every 3 months? Sounds like someone isn't following Microsofts policy and turning off mandatory password changes as they aren't more secure, than picking one and staying with it!

https://arstechnica.com/information-tech...-obsolete/

[slyexe]

Someone mentioned to me that there are thermal restrictions on the 3090's and I wouldn't be able to use more than one of them.  Slyxe I see you were using two RTX 3090's.  Could you give me some insight as to what your build looks like?

Thermals are more an issue in the cryptomining scene. Mining ETH or other coins is hard on the memory chips of GDDR6X which would be the issue I would suspect you're talking about. As for my cards they are under 2 months old and I believe the manufacturers have addressed the issues with the thermal pads on the memory. My cards memory chips usually hit 85-95ºC which is "safe" in my opinion as the memory temperature threshold is set to 110ºC. However, mining and cracking are 2 completely different topics and also totally different aspects of how a video card can be used. I usually have some 120mm fans plugged into the fan expansion slot on the video cards to put on the backplates to cool the memory but had recently given them away and haven't had any issues.

If you're thinking of expanding, beyond 2 cards, I myself do not have much experience in that aspect. However, I would say a server motherboard would offer the best features for such case. I think one of the hashcat developers had a company that handle specially designed rigs - Google Sagitta HPC  for more info.

Here is what the rig I have looks like, it's nothing special.