Sound crackle, game lag

So today out of nowhere, "well previouslly I installed game called "TERA" and after it this started but I unistalled it and it's still the same" when I listen to music, any sounds especially when sounds get louder, sound starts to cracklle, familiar to static but crackle, also when I play games, fps is lower now, it sometimes freezes, crackled when game appears to make sound and etc. Sometimes video card turns off and on bottom right it says "Nvidia bla bal bla has stoped working, reconnected bla bla" I have no idea what that is, I changed my Headphones to other ones, I checked temperature of both CPU and GPU, are both fine 30-50~ as it usually is. Unistalled game that it (might off coincidentally) ruin it but I doubt it was that.
I really need help, reinstalling windows and downloading all the stuff with slow internet again will be pain for me.
p.s I installed new drivers for video card too. PLEASE HELP :(
 
Also, was just watching a video and "nvidia has driver kernel has stoped working' appeared again and video froze :/ btw my specs are i5-2500k 4gb ram gtx 560 windows 8 pro
 
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