GTX 680 SLI fail !! help

[billtaco]

MB MSI X79A-GD45 8D (MS-7760)
Ram DDR 3 GSkill 4G x 4 1333 (No OC)
CPU HexaCore Intel Xeon E5-2620, 2300 MHz (23 x 100) (No OC)
Card MSI GTX 680 4G 2 way SLI

My 2way SLI fail under the driver 301.42 or 304.79
==> Win 7 Windows Aero and 3D points all the same as single card as 7.3 only


I have changed 4 different SLI bridges but still fail
also run all games just like the same performance as one card

this MB support PCIe 3.0 and GTX 680 also work in PICE 3.0 ??
but my
NVIDIA inspector and driver control panel all show PCIE 1.1 and 2.0 only ??

in GPU Z ==> it seems my SLI is success ?? but only PICe 2.0 only in two cards
but in truth ==> Two problems still persisted
1. even lower or just the same FPS in many games (such as Sleeping dogs ==> single card as 37 FPS but only 11 FPS in SLI under the lastest driver)
2. still flashing in many websites on Google chrome

I set the two cards in Slot 1 and 4
furthermore, I altered the two cards in the slot 1 and 2 then only one card can be detected but returned to show two cards after switching back

what is the most possible problem ?? Cards or MB ???

Thanks~~~~~~~~~