I just made an account to leave you guys an answer (lol); well, here it is:
While your computer is turned on, your Windows account is logged in, and your Realtek Audio Manager is open in the Sound Manager window (the one that shows the Speaker Configuration), unplug the BLACK jack for your 5.1 speakers, then plug it in again. You will see a pop-up asking you what the device is, and this is where you can tell stupid Realtek that your speakers are in fact side speakers and not rear speakers!
This is how I solved my Realtek HD Audio, center, side and rear speaker problem. Went to Control Panel, clicked Sound, double clicked my Speakers on the Sound popup menu, on Speaker Properties menu , scrolled down to and selected DTS connect option. All speakers are working fine now.