Unfortunately, what you've written indicates that while you might have upgraded your computer's speed and graphics, you have managed to degrade its audio. You're hearing the crosstalk between the motherboard's digital and audio circuitry. If your computer's video card has an HDMI output and your receiver has an HDMI input, you might try using that instead.
Marantz SR7009 avr + MM9000 amp --> Atmos 7.1.4
Fronts=NHT 2.9+AC2, FH+TM=DefTech PM1000, LCR+TM amped