high cpu usage lag+static audio

[R_SooNami]

i have been recently experiencing unusual fps lag in counter-strike and stuttering in youtube. Before my csgo ran at 55+ fps high - vHigh settings with aa, now it is unplayable dipping down to 20s, i've tried lowering settings but makes little difference. Lag is worst when people are firing aks. I have also experienced lag while watching youtube videos. the video stutters, produces static noises (crackles) and distorts audio. I can replicate this lag and audio distortion alsmost everytime if i scroll up and down when in Steam as steamwebhelper.exe uses 40-50 % of my cpu when doing so. I dont know what is causing this problem as my computer was fine for a long time.

 

Things i've tried:

Turning off and on. lol.  

Updating drivers with driver booster 3. 

Scanning for viruses using Panda, malwarebytes and windows defender.

replugging peripherals

using different peripherals

turning off windows aero helped a bit

disabling/enabling audio drivers

 

temperatures are normal

specs:

intel q6700 2.66 ghz / 40c idle/ 61c while in csgo

mb asus P5KPL-CM

4gb ram ddr2

gigabyte gtx 650 2gb factory overclocked/ 36c idle/ 55c in csgo

NO SOUND CARD

VIA HD audio

HDD old and nearly full

Windows 7 prof 64bit

 

any ideas on cause and solution? is my computer just dying ?