Three views shown.http://www.revolutionpc.net/store/Asus-Essentio-Ultimate-Desktop-Computer.html
Scroll down to the photos towards the bottom.
Looking at the Front of the computer, the LEFT Side panel removes.
Remove the Philips head screw located towards the Top, on the Side Panel's edge, and the Bottom screw on the Side Panel's edge.
Pull back on the raised fingergrip, formed out of the back of the Side Panel.
The panel pulls back so far, then is tilted out, and removed.
-> FOLLOW Anti-Static Precautions
Your body carries Static electricity. Static WILL fry out (Short Circuit), the delicate hardware components inside a computer.
Relieve your body of Static BEFORE reaching inside your computer.
Computer on a table, computer Unplugged from power, computer case open;
TOUCH an unpainted surface, of the metal frame of the open computer case.
This action will relieve your body of Static.
IF you leave your computer in the middle of working on it, be SURE to Touch the metal frame again upon your return.
You may also wish to remove all cables from the computer, and lay it on it's side for easier access to the motherboard.http://www.ebay.com/itm/OEM-ASUS-ESSENTIO-CG5270-P5QL-VM-MOTHERBOARD-61-MIB8Q3-01-US-TESTED-/170893854322?pt=Motherboards&hash=item27ca114672
Look at the right side of the motherboard, and the two long White PCI slots.
Above them is a long Blue PCI-Express x16 slot. This is used for a graphics card.
Above it is a small White slot. This is a PCI-Express x1 slot.
If a PCI slot is open you can use it for a Sound Card.
If not, and the white PCI-Express x1 slot is open, you can use it.
Examples of Sound Cards used in a PCI slot, and a PCI-Express x1 slot;
On the back of the computer case framework is a small 'door', that holds the expansion cards in place.
The Thumbscrew is loosened, and this allows the door to swing open.
Find the appropriate expansion slot cover, that matches up to the slot your wish to use, and remove it.
Note that the expansion slot covers, do Not line up inline with an expansion slot on the motherboard.
(Expansion Slot; i.e., PCI, or PCI-Express x16, or PCI-Express x1 )
The expansion slot on the motherboard, is usually one space over from the expansion slot cover on the back.
[Don't believe that is worded correctly, but you will see what I mean with the Side Panel off, and looking at the motherboard ]
Yes. It's a lot of fun(?) trying to keep the expansion slot covers in place, expansion cards in place, and trying to close that 'door' properly.
[Look close. The bracket for the expansion card, (In this case a Sound Card), fits in little depressions in the metal framework of the computer case; or the brackets half-moon hole, will fit over a small peg, in the computer case framework ]
For additional questions please post in a Comment.