You do have the onboard chipset/sound ports, right?: You may get by with that until you obtain a decent sound card. Sometimes onboard sound is pretty good--even outstanding. (You may enable and disable the onboard sound chip in the BIOS settings.)
Given that your onboard sound chipset is dead--or that the ports have lost integrity--many simple USB dongle devices prove available to fill in. Akin to the Turtle Beach Amigo II, generally they're analog stereo and relatively economical. With some such devices, the mfrs. indicate that 7.1 sound proves available--sure!
You may find that it's beneficial to own such a device, anyway--to fill in when your sound craters or when you have vexing config issues. (You then adjust USB sound codec settings--not sound card/onboard sound chip settings. The USB sound codec comprises a completely separate audio software system from those--proving quite clever. Certainly, using the USB sound codec often proves essential in today's musical instrument USB I/O box interface world, too.)
Again, the promise of USB 3 proves thwarted--fabricators prove glacially slow to adopt USB 3--forcibly, they still insist that you stick with USB 2. (USB 2 really isn't very good with media--it's best intended for relatively simple input devices such as mice and keyboards--USB 2 dongle devices are pretty simple too, though. Sound should prove satisfactory, if limited, for your purposes here.)
In the musical instrument USB I/O box world, PC latency (slowness) becomes a looming factor: As indicated by the previous erudite post, USB isn't as good as PCI or PCI-E--it's an interface which is far more "divorced" from the sys.
The criticism of onboard sound often includes mainboard crosstalk interference issues--generally that's been alleviated a great deal over the years. Given higher-level mainboards, onboard sound capability may prove quite sophisticated--as well. Indeed, you may instead consider getting a better mainboard for your audio needs....