Dual graphic card system can not use X server

My system is Dell690 with dual Quadro FX3500. After I finshed all the installation of suse11, i found the X server can not be launched. Also I tried with latest drivers from Nvidia, but it is still not working.
Is there any additional SLI driver for this?
“sax2” command always died. I’m very depressed of this. Who can tell me how to solve it, Thanks!