well i have a ZOTAC GeForce GT 740 DDR5 LP and the fan goes over the PCI-E slot ,its a single slot cardYou can fit a GFX card and sound card.
If you have an APu you may be able to crossfire a certain gpu with the GFX core built-in to the APU.
Or you can disable the APU GFX core and just use the gfx card.
Assuming the gfx card is double width that leaves a PCI slot to fit a sound card, if the gfx card is a thin single slot style then you can fit a PCI-E sound card.
That will cover the 1X PCI-E slot, means you will have to use a PCI and not PCI-E sound card.
PCI-E is newer tech.
If you dont play games then do you need to fit the GFX card?
If you get a sound card then you also need good speakers or headphones to do justice.
They are virtual surround sound, so possibly some sort of wizardry going on in the actual headset from a stereo source.
I like the Soundblaster Z (oem or retail) but that is PCI-E.
The HyperX headset are well rated on review/gamer sites.
If you are desperate for a PCIE card and have the spare space in the case you could use a PCIE riser cable and move the card somewhere along.