External (5.1 Powered) Speakers No Sounds

Hello, this started a few years ago. Got into gaming. At first, no problem picking between headset and external speakers, then slowly change, do no sound. I can pick either one, headset/mic always works. I can listen to music and movies through headset. Did a complete new install of Windows 7 onto an SSD, my Steam Games are on another SSD, also installed a new 2 Tb hard drive or general stuff. I have Realtek HD Audio Manager installed ( same as when i first bought the computer ). The sound bar ( when I pick external speakers ) rises and falls with audio, but noting to speakers. When I set up the speaker config and test, I see each speaker being activated, and I only hear a very low Bzzzz/Humm, from each speaker as it's being tested. The external speakers are selected as default, ran audio troubleshooter, downloaded/installed/uninstalled Realtek Audio manager over and over again, drivers too. Nothing has helped. Here are my specs:

OS: Windows 7 Home Premium 64-bit SP1, Desktop
CPU: Intel i7 2600, @ 3.40GHz
RAM: 16 Gig
Motherboard: Dell Inc., Model: 0Y2MRG (CPU 1)
Version A00; Chipset Vendor: Intel
Chipset Model: Sandy Bridge
Graphics: ATI AMD Radeon HD 5700 Series
Storage: Western Digital 2 Tb;
Samsung SSD 840 EVO 250G SCSI ( Steam Games )
SanDisk SDSSDA240G SCSI ( Windows 7 OS )
Audio
Sound Cards
High Definition Audio Device
Realtek High Definition Audio
High Definition Audio Device
USB Audio Device
Playback Devices
Speakers (Turtle Beach PX22) (default)
Speakers / Headphones (Realtek High Definition Audio)
Realtek Digital Output (Realtek High Definition Audio)
Recording Device
Microphone (Turtle Beach PX22)
I have checked the speakers unplugged with another device, they work great. When I plug them back in, the computer knows and says you've plugged something in, color coded cables to color coded jacks on back of computer. They are self-powered, and the volume control is turned all the way up. They are Creative 5.1 Surround Sound. Also, the computer came with THX TruStudio PC, I reinstalled it but it didn't work, so I uninstalled it. I would like the speakers to work so I can listen to movies/music. OR, I can get a USB ? converter? to plug in ? Any suggestion, advice or U can just say well you're @#$%^&* ! Thanks

The model number shown is for the motherboard.
The model for the machine? It's an XPS 8300
Dell Service Tag Number? Not quite sure what you mean. I looked at mine on the computer and there is noting in my posting that resembles that number.
Yes, the "Speakers" (Realtek) are set as default playback device.
Both High Definition Audio Devices have been disabled, then I rebooted. Still nothing. I still hear a faint Humm from all speakers, volume turned all the way up. Tried to config the speakers again and tested. The volume bar goes up and down still like there is audio, but nothing for the speakers.

Yes, the speaker systems are plugged in properly, color coded, green-green; orange-orange; black-black; fully inserted, all the way. the connections on the box ( Creative ) have never been changed, they worked 5 years ago, never needed to change them. I did go ahead and pulled the box and checked the plugs, they match up.
Yes, I've plugged my headset and several others into the green jack; the computer even tells me I've plugged something into the audio jack. but no, no sound, i can see the sound bar rising and falling, and yes I selected it as the default and made sure the PX22 was deselected and disabled before I started.
Is there a way to test that section of the motherboard? Or, is it just missing an audio driver. I've been to Dell and D/L their audio file/drivers for my system thru their Dell Detect software and using my Dell Service Tag number and D/L a bunch of other files / drivers for my system.
Everything else is working fine. If my computer knows that I've plugged something into the audio jacks, does that tell me anything?
I've tried Goggling my motherboard model number, found some refurbished mobo's. But nothing that would give me an idea as to what driver I would need for get those audio jacks to work. Is there anything available that would run a check on that particular part of the mobo for the audio jacks?
What do you think about just getting some kind of USB external sound card hook up? I had some guys I was gaming with said to go to Amazon and get one of those. And they're CHEEP !!

Yes, I know it's a Realtek on the motherboard. And no, there is no sound card, never has been one. Yes, I went to Dell and D/L everything they had for my computer, numerous times over the years, back when this first started and after the new upgrade. Dell wanted $295 for a years worth of out-of-warranty support, and guaranteeing that it would be fixed. For that kind of money? Nope, I'd just go to Amazon and get one of those USB external sound cards. But, I was hoping someone here might have some experience with this problem. If not, I'll just go to Amazon for my fix. Thanks