I see no reason to use a 30 second exposure for product shots, especially if you're using a tripod and flash. Such a long exposure time will introduce blurriness when either the camera, tripod, or computer case moves (as seen on the Corsair logo on the first picture, or on the third picture with the Asus logo and the cable).
Close your aperture down too, using such a small aperture makes your pictures prone to softness through diffraction.
If you're going to include both your warmly lit room and your lit-up case, your camera will adjust white balance for one but not the other. Since your subject is the case, adjust your white balance for that - white balance is way too cool as it is and everything inside your case looks blue.
Read up a bit on commercial/product photography, or at least look at some examples for inspiration. Clear out your desk if you're placing your computer there, and do not include any other elements (keyboard, mouse, etc.) unless they complement the computer in the picture's composition. I would also unplug every cable except the one feeding power, and try to leave it as out of sight as possible (use gaffer's tape or whatever you may have). Use macro lenses (or close-focusing lenses + some cropping) to take pictures of internal components.
I must admit that I'm jealous of your cable management! When I built my computer almost two years ago I just put everything in there, and as soon as it turned on and worked I closed the case... I'm afraid of opening it knowing the mess that awaits me so I haven't opened my case ever since 'p'