no previous cracks needed, although it would make sense to try crack the example hash from https://hashcat.net/wiki/example_hashes just to make sure everything is working correctly (you could either just put the word in a new dictionary file, or create a dictionary with a few dozens of words of which one is the correct one).
If you have a dictionary file for which you know a lot of passwords won't be the correct ones, you could just filter / modify it externally with something like "grep" (linux, there are many windows equivalents). Create a new filtered dict and use it in hashcat instead of the original one.
Cracking shouldn't be a problem for MultiBit and yeah I tested some examples, but not very long "realistic" runs unfortunately. Maybe others did, I'm pretty sure about that.
MultiBit HD uses scrypt, so you should probably test with your CPU instead of a GPU. A very performant modern Intel CPU (i9 ?) or even a very new AMD Ryzen processor could be faster (but this depends a lot of how many GPUs you have etc... normally you could put much more GPUs on your motherboard than CPUs, there are exceptions of course).
To improve the speed (at least a little bit) you could/should also use -w 3 or even -w 4 command line options (see --help).
Good luck
If you have a dictionary file for which you know a lot of passwords won't be the correct ones, you could just filter / modify it externally with something like "grep" (linux, there are many windows equivalents). Create a new filtered dict and use it in hashcat instead of the original one.
Cracking shouldn't be a problem for MultiBit and yeah I tested some examples, but not very long "realistic" runs unfortunately. Maybe others did, I'm pretty sure about that.
MultiBit HD uses scrypt, so you should probably test with your CPU instead of a GPU. A very performant modern Intel CPU (i9 ?) or even a very new AMD Ryzen processor could be faster (but this depends a lot of how many GPUs you have etc... normally you could put much more GPUs on your motherboard than CPUs, there are exceptions of course).
To improve the speed (at least a little bit) you could/should also use -w 3 or even -w 4 command line options (see --help).
Good luck