Gpu Limit
I'm looking to build a password cracking setup as a project

I know someone that wants to sell 24 x RX570 out a mining rig. I already have a asus extreme motherboard and a amd 3790x cpu and a 1600w power supply , the power supply I'm sure Im going to maybe need two or three

Can anyone advise me ?

Is there a limit to mulitple gpu's i.e risers etc with hashcat etc, or what would I require to be able to get 24 x RX570 work, or is what I'm trying to do not feasible and a waste of time, if so can advise and explain any info/help would be appreciated 

EDIT : so quickly looking into pci spec , I'm guessing I'm restricted to 6 to 8 per motherboard via risers, so in order to use more than 8 I'll have to add more motherboards/powersupplies. can you setup three motherboards and 24 x RX570 as a slave and use one more motherboard as the primary to get hashcat to utilize all the gpu's ?

After looking for motherboards I found the asus b250 19 gpu mining board
has anyone tried using this with 19 gpu and hashcat ???
1. Don't buy AMD cards for hashcat.
2. How are you going to cool that many GPUs?
3. Mining rigs are not usually what you can use well with hashcat. They are lacking RAM and for most attacks you will want to have more than a PCIex1 connector.
Thanks for the responce

Yea I've been looking into it more, and your right, amd is a not a good option,
the Cooling option was fans between the cards

I was hoping to use the rx570 becuase of price of cards , the person selling this mining rig has 30 gpu rx570. I could have spare cards

alternative option is 19 nvidia 1080 + board + cpu + ram + psu + cables + mods = the wrong side of $20,000. this is only a cheap project I was getting the mining rig for $3,500 to get my feet wet in password cracking , I went to see the mining rig in his house , he just wants to get rid, all cards are working

I dont really want to spend $20,000+ to be able to try crack some passwords , and as password cracking is more an enthusiast thing, you'll never crack all passwords no matter how big your rig, setting aside the whole rule set etc and varous techniques to increase sucess rates there is a lot of password you just wont crack

I have comtemplated spending $20,000+ on a rig, but while I just dont have $20,000 like its $10 stuck down the side of my couch, in otherwords to spend $20,000+ to be able to crack 20-25%% of passwords, just doesnt seem like a worth while use of money,  and that cracking percent is a generous percentage
what cards would yeild a good result for cracking passwords without spending my lifes savings and buying 13 x 2080ti's

If I use the B250 board I can get 13 GPU it wont except 19 unless you add some p106 mining cards

If I bought 13 x ZOTAC Gaming GeForce GTX 1660 6GB GDDR5

Do you think that would get good results
What type of hashes are you going to crack and what attacks do you plan to run?
hashes :  md5 sha3
method : bruteforce

I found 1070 gtx 8GB on newegg for 300 , I think Ill just bite the bullet and buy 13 of those and maybe the ASRock H110 Pro BTC+ over the B250 the B250 seems to have numerous problems with reliablity accord to some people on forums

with that setup do you think I would have enough power to crack a decent ammount of passwords ?
If you are only going to do bruteforce you might get away with a repurposed mining rig, but you should be aware that those will have low performance for pretty much everything other kind of attack and most of the other attacks will likely require much more RAM than your average mining rig has (recommendation is RAM >= VRAM).

I don't know how familiar you are with hashcracking in general and for what purpose you are cracking those hashes but I want to point out that bruteforce is usually the very last resort and generally not very useful compared to other attacks.

If you are positive the limitations outlined above don't apply to you and you will be able to handle cooling such an array of GPUs go ahead. Regarding the GPUs you are buying, have a look at the benchmark values, for example here:

Check the $/hashrate rate to decide on the devices you get. It's generally much better to go for less devices (less heat and power) if the rate is close or better (disregard AMD cards). And of course make sure the cooler/fan is appropriate for your cooling solution.

You have been warned.
Is there a reason you feel the need to buy 13 of anything?

If you're just trying to get your feet wet as you put it, maybe buy 1-2 1080 Ti's? You're rig could be substantially cheaper not to mention easier to deal with and cool and still be plenty powerful for normal needs.
First off Thank you for your opinions and replys , I posted here because people like yourself are experienced and very knowledgeable

To answer the question about 13 of anything, isn't more power better ? What i'm trying to achieve is a cheap build, but plenty of power , a poor mans brutalis. I'm well aware the brutalis is purpose build and very powerful due to its specfication but again I just can't justify spend $15000+ on a hashcat rig

spending budget $6000-7000 I have sourced the parts on new egg and I have two build options




PSU X 3 : corsair AX1200i


CPU : Intel Core i7-7700

GPU X 13 : ASUS GTX 1070 8GB Dual OC Video Card DUAL-GTX1070-O8G

Question ? if you have $6000-7000 to spend on only a hash cat rig would you do what I'm doing, if not why ?

I could opt for 3 x 2080ti gpu amd motherboard with a threadripper 3790x but would'nt that not be as powerful as 13 x 1070 ?

the 2080ti might be refurbished ones, I alrteady have ram and a PSU that will work with this build
Take a look at this one:

Although, I would not build it again the same way as I did back then. In terms of GPUs, you should defintely use the blower style cards from EVGA, e.g. this one

As fans, we used enermax d.f. storm, which do a really good job so far.