Audio lag appearing in games causing system lag

Certain games are affected by this lag. The game will run smooth for a while (regardless of graphic settings) but eventually the audio will start crackling. Then graphical lag will begin. Changing the graphics from high to low does nothing and the lag persists for a while after the game is closed.
Thing is, setting the affinity of the game to one core prevents the lag from turning up in the first place, however, when set to 1 core I need to have the graphics set to minimum or suffer graphical lag (which stops when settings are set down).

When this first appeared I noticed that audiodg was using about 30% of my cpu. Took advice and changed my sound settings which got it down to 5% at worst. Now my CPU stays at about 70% during the lag and memory is in the 80% range. So I dont get what the problem is, if my cpu and memory havent hit max it shouldnt lag.

I figured it must be an audio issue and disabled my audio device. No lag seemed to be present anymore but sound is important in game. So I have a choice between low graphics or no sound, both of which ruin the experience.

The audio device is realtek and microsoft when realtek is unistalled, both cause lag. my drivers for audio and graphics are upto date.

Can anyone help me figure this out? Im not very computer savy so I cant find whats causing the problems.

*Some games that lag have support for duel cores others only single
*All games optimised for quad cores run perfect on my computer

Ok so I realised that when the audiodg was a problem I turned off all services, as I thought the problem was too many services running. Then I turned the services back on except I made a mistake and all services got turned on as automatic. So I had to find which ones were needed and which ones werent and change thier settings.

Anyway, I decided I may have left services on that were causing the problem and have begun turning them off one by one to see if it helps.

Turned off Agere Modem call progress.

The lag still turns up, however, the audio crackling is very quite now. Id say its about a tenth as bad as it was.

Still no solution to this. Removing some of the services has gotten my cpu down to 60% during the lags. I cant figure this out at all. I thought it may be a graphical thing (though its strange that it boggs down the entire system) changing graphics does nothing to prevent it.