GPU Issue + Hardware Reserved Memory

Two issues I had:

1. After installing a sound card Windows 7 was failing to boot. It was getting stuck on the "Starting Windows" screen. Long story short, it worked after (among other things) moving the graphics card to a new slot. No idea why it happened at the exact same time as installing the sound card. I guess I might have bumped it while messing around in the case.
2. After all the troubleshooting I did for the above problem, I noticed that only 8 GB of my 12 GB of memory were showing up as "usable" on the window that comes up when you right click "Computer" on the start menu and go to "properties". I reinstalled the memory sticks one at a time and  eventually all 12 GB were usable. I assume I didn't install a stick all the way after re-adding them before.