Crackling/popping noise from speakers/headset

Hi all,

This is my last hope before I send my laptop off to Asus for them to look at the problem.

Basically, I have horrendous crackling/popping sounds coming from my Asus G750JW laptop speakers/headphones.

Since I bought the laptop last year, the crackling has existing from the speakers. 99% of the time however I have a headset or earphones plugged in and there was never any crackling sound. 

Yesterday I formatted the laptop in order to return to Windows 7 but the crackling problem has got worse - it is now unbearable from the speakers AND through a headset/earphones. 

I feel like I have tried everything to solve the problem. I have tried numerous audio drivers and read a lot about this issue being caused by DPC latency but I have not been able to isolate a device that is causing this latency - I have disabled display driver/network driver etc in device manager to see if it solves the problem but no.

I know when the problem occurs...it is whenever the CPU is running at it's full 3.2GHz. For example, I can be watching a film with the processor running at 3.2GHz and the crackling is terrible but when I turn the inbuilt Asus power mode down to 'power saving' which reduces the CPU to around .77GHz idle, the crackling completely disappears. 

Obviously though, when FSX is being used, the CPU is always at 3.2GHz so I have this problem. I have emailed Asus about the issue and all they have suggested it to send the laptop in for them to have a look but if there is a solution I would like to avoid having to do this.

Many thanks.