What is the best video card for brute force?

[niceguy123]

Can you explain a bit more about that - " the 8x 4090 would be best but ONLY if you are NOT using risers. If you are going to use risers, things get a good bit more complicated as they can cause serious issues. "

Isn't the x1 speed only affecting certain types of attacks? And even in that case just loosing some performance because of it?

You've actually highlighted a part of the issue beautifully without even knowing it. The vast majority of people getting into this, yourself included, are familiar with the x1 risers like miners use, like the USB3 cable style risers. Those are what I was primarily referring to and they are the source of all the riser issues we see.  x1 risers, beyond just limiting you to x1 lanes which, as you've pointed out, will certainly impact your performance, also almost always wildly deviate from anything close to the "spec" for PCIe. The amount of tx/rx errors you will see due to interference, which will further impact performance or cause GPUs to be completely inoperable, tend to be drastically higher on risers like this. If we ignore the limited bandwidth and horrible interference, they are also typically not built to the quality standards or design standards they should be to handle the load they are put under, which can quickly turn them into fire hazards. x1 risers like the USB ones miners are often seen using are NOT something you should be using for HPC workloads that stress the bus and/or cause the GPUs to draw significant power. Mining does neither of those things and so the corners they cut in building them don't have as significant of an impact. Comparing hashcat to mining is a really bad idea, they are not the same kind of workload.

Now, the reason I said it gets more complicated is because there are risers out there that are good quality and built to a specification that makes them usable for hashcat and/or other heavy HPC workloads. They offer good bandwidth at x4 or x8, they offer good signal quality and low interference, and they offer stable power without the risk of melting. They are also relatively expensive, with some going for hundreds of dollars per riser. Not the kind of thing your average user is going to want to pay or generally know how to even look up. If you are looking for a system integrator to put a system together for you, they aren't even an option for you, so there's no real point in bringing them up. If you are looking to build a system yourself, you've got to select the right motherboard, CPU, etc. to even be compatible with such risers and so it's a major consideration with some major costs. I will, tentatively, be releasing an updated guide that goes over some of this stuff to try and help people understand their options better, but I can't promise that will be any time soon. For now the best advice I can give is to stay away from ANY risers as much as you possibly can.

I  agree as a whole BUT by specification the PCIe should not provide anything more then 75W. Yes if you use the cheapest raiser possible you would probably have many troubles with them. But then again I build miner looking like machine for hashcat with couple of 3090s and in benchmark, I am getting same speeds, as benchmarks you have posted on this forum. I've been putting them on 10-12 hours long work and did not observe any troubles with the raisers I've used. I had some troubles and it turned out, it was the aggressive undervolting I did on the GPUs. I wrote about it in another thread. Time will tell and they are probably more prone to failure then the one you wrote about.
I totally agree that you have to select the right motherboard and CPU with "hundreds" of PCIe lanes to get the best possible performance etc. but as you said this comes with some major costs. For us mortals some reading and thinking could give us something to play with, without loosing a kidney or two.

Actually if you can send me some more info about the raisers that are built to a specification, I would be really grateful!