Mining rig gives little speed increase

[LittleGrand]

There are two bottlenecks when running a dictonary attack with this setup, because candidates are processed by the CPU first and then distributed to the GPUs:
1. A presumably shitty CPU
2. GPUs, which are probably connected with USB Risers

This is exactly the reason why mining rigs are not suitable for password cracking. Have a read here, if you want to know more about hardware recommendations for password cracking: https://passwordvillage.org/hardware.html#rig_setup

Shitty GPU is the problem Id say(probably not enough ram as well).  Need GPU+2 threads available, mine is dual core..... I also should be using -d 2 so the CPU is not used for the hashing from what I read.   The Risers on mine are correct for power draw as I do not use the terrible built in connectors I actually use the 6pin.

Is a brute force attack the same limitations?(sorry I am new to this)

Thanks