so i'm not sure if i should post this here or not but here i go anyways. i recently built my first computer. everything's working well with one exception. every time i shut down my computer, i get this weird screeching sound for a couple of seconds before it powers down. i changed the speakers and i get the same sound, i even changed the ports from the case to the motherboard audio jack and i get the same noise. i even reinstalled the audio drives for my asus M5A97 R2.0 mobo and i still get it. is the build in audio chip not good? i get fine sound when its on but when it turns off, i get that screeching noise. would buying a sound card fix this? what does it look like the problem is?