Mint13 Cinnamon 64bit Surround Sound not working, onboard

[phelix9]

Gigabyte 78LMT-USB3 with 3 audio jacks in rear, running Maya 64 bit with Cinnamon, but ran into a problem; due to HDMI output, I apparently have two audio chipsets. One is the 'AMD nee ATI RS780 HDMI Audio [Radeon HD 3000-3300 Series]', and the other doesn't even show up as audio in the system information. I know it's Realtek, but the only Realtek device is the ethernet controller; 'RTL8111/8168B PCI Express Gigabit Ethernet Controller (rev 06)'. I have an older Logitech 5.1 surround system that has 3 analog jacks. In Windows, not a problem; the Realtek software detects that I plugged in a device, and asks what the device is. In Linux Mint, I get front audio (L & R), but nothing from the rest. How can I fix this issue?

I am a hardware guy, software is not typically my gig. Consider me smart, but a Linux noob.

This is a multiboot system, and I require Linux to run GRUB, and am attempting a total changeover to Linux, except for my gaming needs (until WINE offers full acceleration for graphics.).

Different note: My CPU is running 3 underclocked cores, and one correct. Why is this?

[remoulder]

Have you checked the settings in Sound Preferences under the Hardware and Output tabs?

[phelix9]

Yes, indeed I have. I can only get the front speakers working.