Video Memory

[l008com]

I have an RX 480 with 8 GB of RAM that does a great job of hashing. I also have a GT 120 with 512 MB of RAM that would probably be absolute garbage at hashing. But it doesn't even have the chance because hashcat says the card doesn't have enough memory. So how much do you need? I was thinking of buying another low end cheap card or two to give my setup a little boost, if I get a 2 GB card, will hashcat still run on it?

[royce]

Many attacks might have trouble fitting into 512MB, even if all 512MB could be used (with CUDA). But when using OpenCL, there's a maximum allocation of 1/4 of GPU memory (so 128M here). You could force CUDA to see if that helps with you 512MB card (but honestly, such a card is so old that it might not perform as well as a modern *CPU*, depending.

[l008com]

Oh yeah to clarify, I'm not trying to get my old GT120 cracking, I'm solely wondering about RAM because I want to buy another used low end cheapie card, some of which have 4 GB, some have 2 GB. I don't think I'll be looking at another 8 GB card. And I haven't seen any 1 GB cards for the type of card I've been looking for but who knows.

So I'm just looking to understand how much video RAM is required on the card so that the card can crunch at it's maximum speed?

[royce]

Ah, yeah. It really does depend on the attack, unfortunately - can be all over the map. If the goal is to support a wide variety of attack types, including stacking multiple sets of rules, I personally would consider 8GB a minimum (but I do a lot of attacks that eat a lot of memory) ... so if 8GB is too much, I'll get as close to that as I could.

[l008com]

Well I'm not entirely sure what exactly you mean by attack type. If you mean which hash algo then I can tell you I'm pretty much only going to be using -m 16700 to help people get back into their Macs when they forgot their password.

[l008com]

Is there any way to figure out how much memory is the minimum I need or does anyone else know?

I'm pretty much only working on FielVault 2 and I'm currently running an RX480 8 GB that works well and I'm thinking about getting a second RX 480 4 GB to help. But I don't want to buy the card if it's not going to be able to do the task?

[royce]

Concur.

[slyexe]

Well I'm not entirely sure what exactly you mean by attack type. 

Royce is referencing different attack modes which hashcat uses. Such as Bruteforce, Wordlist, Hybrid, Rules, and whatever else you possibly plan on using for your cracking sessions. This changes the way hashcat distributes the load using VRAM, so as Royce said buying a card with 8GB VRAM is recommended for a wider range of attacks.