Extreme lack of benchmark score/added fps by using 2 video cards inste

First off my computer is a 720 h2c with windows media center. it came with 2 nvidia 8800GT video cards which were 256mb each in SLI mode. With these cards i got a 3dmark06 score of 13700.

I replaced both the cards with just one video card where is a 9800GTX+ from nvidia. The card is 512mb and the 3dmark06 score was 16367. The fps scores were 56, 58, 63, 68.

When I install a second 9800GTX+ same exact card in SLI mode, I get a 3dmark06 score of 18136. The fps scores were just 58.5, 61.8, 90, and 72.

Shouldn't i be getting about double the FPS and a much higher 3dmark06 score with 2 9800GTx+ cards in SLI?

Then again i'm not even sure if I have the SLI setup right in my computer. Anyone know if i need 2 SLI bridge connectors for the 9800GTX+ cards or just use one on the available connect spot closest to the rear of the computer case?
If you haven't seen a 9800gtx+, it has 2 places where you can place the regular SLI bridge connector when the cards are installed instead of 2 which looks like this:

-------------------------====--=--====---
.....................................................||
.....................................................||
-------------------------====--=--====---
the "||" represents the SLI bridge connector.

Any help is appreciated

yes but i think that i need to use 2 sli bridge connectors for my video cards instead of 1.

Anyone have one of these kinds of sli cards?

i'm running a quad core running at 3.6ghz