I can't mine neither on the gpu nor on the cpu

always asks to switch to the gpu after 30 minutes of starting and then asks to switch to the cpu again

It appears Salad is having a hard time running on your system. If you have an antivirus installed, make sure it isn’t blocking any of Salad’s miners. If this isn’t the issue, then make sure that you have enough available VRAM/RAM when running Salad (VRAM minimum is slightly over 2GB, and RAM minimum is around 4GB).