Need help with building rig for RAR only
Hi everyone , i need to build a machine for cracking rar archives , nothing else. Can anyone help me with this , i can thank you with bitcoins for your time and help. Please pm if you can help
It's difficult to give a general answer that fit all situations.

It would be important to know which type of RAR archive you need to crack, hashcat supports these:
-m 12500 = RAR3-hp
-m 23800 = RAR3-p (Compressed)
-m 23700 = RAR3-p (Uncompressed)
-m 13000 = RAR5

they are all very different (especially the RAR3-p hash types that use a hook function with data decompression on CPU).

The other important things that would be important to know is if you want to crack multiple hashes... if you are only targetting one specific hash (or always different/new hashes) .. etc

In general, most modern GPUs (new NVIDIA GPU maybe, like 3080 or similar) would work for RAR archives, but for RAR3-p you also need a fast/modern CPU (Intel i7/i9 or a fast xeon or AMD Ryzen ? ).

This is actually true for most hash types that hashcat supports, but there are some minor exceptions (like scrypt and bcrypt that are GPU-unfriendly).

The important thing you need to know about RAR/pkzip/WinZIp/7z is that hashcat has a maximum data length support... so you can't really run a huge hash with multiple megabytes of data. This is a known limitation, but important to know before you spent a lot of money on new hardware.