You should choose GPU password recovery software. The speed of password searching on video cards can be 10 times higher as compared to CPU. You can enable several video cards and increase the searching speed.

I would recommend AccentRPR or a more general product called Pascovery Suite.

But in any case if a password consists of random symbols, there are almost no chances for success.

It is very difficult to recover RAR passwords. Password validation takes a lot of time that depends on the archive size (an archive shall be unpacked for validation).

That's why your 1.5GB archive is nit the best candidate for success.

In any case you should try.

PS: sorry for the answer in English