sli with 2x 8800 gts's wont work PLEASE HELP

i have a ultra x3 1000 watt power supply
2x 8800 gts 1 is 640 and the other is 320 mb wich nvidia said i can mix 2 cards with diff memory as long as they were the same gpu
nforce 680i mb
2gigs of 800mghz ddr2
duo core 3.0 gighz

Okay, i have installed both the cards power connectors are plugged in the bridge connector is connected properly. And yet the nvidia control panel does not give me the option to enable sli. But when i view the temps in the nvidia monitor view it shows the temp for gpu 1 and gpu 2 so the computer see both cards, however it is only using 1 gpu, there is no enable sli option in my control panel like the pictures others are posting. PLEASE HELP

again i have the latest forceware drivers and nforce drivers installed i have tried flipping the cards around as well as flipping the bridge around. and i get nothing . any advice would be much apreciated

yes as i had said in my post, i have the latest forceware drivers ( wich includes the control panel) still i can see the temp of both cards but yet no sli enable option in the control panel. I tried re installing several times....