Solved! Connected old radio speaker to PC and now crackling and static sound.

[Renekoo1]

So i took some old radio speakers (60w, 8 Ohms ) and connected them to a car amplifier (max 75W 4ohms ) (power is coming from my computer psu ) and now when i connect them to my pc i get alot of static and crackling noise (no static when connected to my phone).
Will the problem be solved if i get a sound card ? (also no static sound on headphones or other speakers while pluged in pc)

 

[americanaudiophile]

I would try not using the same PSU for the car amp and PC.