I'd change most of the system and would buy a
- different mainboard depending on what you want to do with it, but surely not this one; too expensive, Realtek NIC etc.
- different CPU; you either use that CPU for cracking, then get the 6500 for a little more; or you don't then get the 6100 for much less
- memory in 2x4GB configuration (or 2x8GB)
- SSD instead of HDD
- different PSU, since 550W is not sufficient for an upgrade to 2xGPUs
- different mainboard depending on what you want to do with it, but surely not this one; too expensive, Realtek NIC etc.
- different CPU; you either use that CPU for cracking, then get the 6500 for a little more; or you don't then get the 6100 for much less
- memory in 2x4GB configuration (or 2x8GB)
- SSD instead of HDD
- different PSU, since 550W is not sufficient for an upgrade to 2xGPUs