It takes a while to populate if you haven't opened it for a while. Are you leaving it long enough? You could try signing out and back in again from Preferences > General > Account. (via the cog icon top right corner of the Desktop Application Manager) This forces a rescan of your system, so another delay. Ordinarily, it only scans for updates once every 24 hours.
BTW I think you could improve your system considerably without spending too many dollars on a video card.
http://helpx.adobe.com/photoshop/kb/photoshop-cs6-gpu-faq.html
If you do take this route, be sure to disable the on-board GPU in BIOS