My Gaming PC ( GTX 970 I5 4690k CM 212 Evo ) Seems to suddenly be running badly, this includes but is not limited to computer crashes, extreme changes in speed, an extremely weird startup crash, ( The screen became pixelated in different colours in small blocks and crashed with audio sounding like NURRRRRRRRRRRRRRRRR. However sometimes the PC works fine, this morning I started it up and in startup it ran fine yet as soon as the PC was loaded there were some extreme preformance issues, I checked task manager and it said only 50% of the CPU was in use and nothing was maxed out, now I restart the computer end a bunch of tasks in task manager to be safe and it runs fine, I have no idea what is going on and I am currently doing a full system scan with avast *EDIT No Threats Found* *Edit#2 Following an other crash I had avast do a startup scan finding one file, called driveragent doing some research I find that this infact is not a virus but a false positive* *Edit#2 Did a error check on my HD and SSD and it found nothing*