Inspiron 3847, sound card?

Do you actually have an add-in PCIe x1 sound card? This model comes with Intel 5.1 channel HD Audio which is integrated on the CPU chip, not an add-in sound card.

Have you tried a different mouse and/or a different rear USB2 port?

If the motherboard has expansion slots the OP should be able to put a PCI or PCIe sound card in it the question is do they even make them anymore?  the Creative Labs Sound Blaster Line and the Turtle Beach DSP sound cards used to be the big guys in town but I haven't seen much out of Creative and as for Turtle Beach it looks like they have stuck to just making gaming headsets and other related accessories.  If the suggestions the others have tried don't fix it and you go for the sound card fix just find out how to disable the on board sound should be in the BIOS or some boards will do it automatically when it detects one installed.  You will not be able to use the front panel audio jacks with the new card but the rest of your front ports USB, SD card reader, etc will remain intact.  Does the computer have any available front bays?  I'm asking this because some sound cards have an add in board that goes in one of those bays and that replaces your front panel audio as well as gives you controls for tweaking the EQ settings and so on.  

Dell never tested a discrete add in sound card in this model. The online Inspiron 3847 Owner’s Manual shows us that the motherboard has two PCIe x1 slots, but no PCI slots. So in theory, any PCIe x1 might work.

* Restart the Inspiron 3847
* Press F2 to enter the BIOS
* Go to Advanced
* Go to Onboard Device Configuration
* Disable Onboard Audio Controller
* Press F10 to Save and Exit
* Allow the Inspiron 3847 to reboot into Windows
* Turn the Inspiron 3847 off
* Disconnect the power cable from the Inspiron 3847
* Open the case cover and install the PCIe x1 sound card
* Close the case cover
* Reconnect the power cable to the Inspiron 3847
* Power on
* Once into Windows, install the PCIe x1 sound card driver
* Restart Windows when done

where do i find that?

Best way around this is to turn internal sound off and use USB Sound.

https://www.amazon.com/Creative-Labs-70SB173000000-Sound-Blaster/dp/B06XBZ38ZJ/

Only Card I would recommend for 3847 is Dell specific card

https://www.amazon.com/Creative-Sound-Blaster-Recon3D-SB1350/dp/B00654PUPA

https://www.dell.com/support/home/us/en/04/Drivers/DriversDetails?driverId=241T2

yeah ive asked around on amazon also and people have used this sound card in this machine with good results too: https://www.amazon.com/gp/product/B00EO6X4XG/ref=ox_sc_saved_title_4?smid=ATVPDKIKX0DER&psc=1