Assuming the SoundBlaster sound card is OK, there are many reports, here and other forums, of Popping and Crackling in Windows 7 systems (and some on Win 8 systems).
Unfortunately, there is no "one fix" for the problem. It can be some system latency issue, a bad sound driver
, a video driver, Wi-Fi connections, etc.
The first and easiest thing to try is to "reseat" the soundblaster sound card. With the PC powered off, remove the card then reinstall.
Run the DPC Latency Checker
program and see if that shows anything.
Some motherboard monitor/control programs have been known to cause this.
Reinstall the latest sound drivers
, from Creative, and the latest NVIDIA video drivers.
EDIT/ADDED: You can also remove the Soundblaster and go back to using the in-built sound on the motherboard to see if that also has the problem. Also, DO NOT have both the integrated audio and Soundblaster both enabled. This can cause conflicts and many problems. Disable the integrated in the BIOS when using a separate sound card.