Sound Crackling Problem

Hi, I'm currently having a problem i cant seem to figure out the cause. I've been using my onboard Realtec HD Sound on my Gigabyte GA-MA790X-DS4 790X board for a while & then over passed 2 weeks i've noticed sound pops & crackling whenever i listen to music or watch movies & even when my windows loads up it crackles.

What ive done so far...

Uninstalled & reinstalled drivers
Uninstalled & installed older drivers
Uninstalled & installed Microsoft's default drivers
Checked Speakers & headphones & both work fine on my other system.
Uninstalled all codecs & reinstalled codecs.
Downloaded Different media players & tested.

Ive purchased a Speedlink Stage 7.1 PCI sound card to fix the problem & after installing drivers i still have the same damn problem.

I'm currently using windows 7 64bit since its official release & only had this problem for 2-3 weeks now.

I'm suffering here guys, my sound is needed for audio editing & video editing so please can someone suggest some possible fix's.

thanks

I realize this isn't particularly insightful, but I suggest making sure it isn't a physical problem with one of the connections. Try new cables and speakers/headphones, then make sure the audio out jack isn't bent or damaged. If reinstalling drivers doesn't fix it, there may be physical damage. Perhaps even on the card itself if nothing else fixes it. Also, it might not be a problem with the card or drivers if your computer is in general struggling so more ram might help. But that would only be the case if you have a notably old computer or the system is stressed.
One other way to diagnose this is to try different input. Play from a cd and from the internet and compare. If there is a difference that will hint at the problem.

One other option is to do a quick search for drivers on the internet (they should be free and easy to find) and hope that the drivers from another source work better on your system. Maybe even drivers from a slightly different model (but I have no info about this so be careful).

Lots of fine technical info but the obvious question are..

i. What loudspeakers are you using, have you tried another pair or headphones?

ii. Are you running the sound card into an aging HiFi amplifier by any chance before it gets to the speakers?

If it isn't the sound card, the speakers/headphones, or the cables in between, I would suspect something on the motherboard.