Yes i have looked at this and thought it would run at 16x but is says in the nvidia control panel that the pcie bus speed is only running at 8x. It may just be that the manufacturer of my board (Dell) has disabled the 16x feature and left the settings at 8x for each slot as default.
Dell didn't disable anything, they simply provided a lower end board that only runs at 8x electrically, they didn't make them they bought them, you could have bought a similar board from Newegg at the time or , having been able to read the specs, opted for a full 650i .
Tests have been done, a long time ago, and there was minimal performance loss between 16x and 8x and that was only with the most powerful cards.
Really isn't a problem.