Help with 9800gtx+ sli

[becton226]

I have two 9800gtx+ that i cannot get to work in sli. I boot up with the two cards powered and the sli connector on and as soon as windows load screen comes up the screen just goes blank.

msi p7n platinum (750i)
e6750 @ 3.2 ghz
ocz ddr2 ram (800mhz)
Antec Earthwatts 750 watts
Win Vista 32bit
nvidia drivers 186.18

I'm guessing this power supply is not getting the job done, it says sli certified but is not listed in the nvidia slizone lists for two 9800gtx.
Any thoughts or suggestions?

 

[Maziar]

Does your cars work in single mode ?

 

[Mousemonkey]

Have you tried all four DVI ports?

 

[maximiza]

try booting with one stick of ram, once SLI is enabled, shut down and re install all ram.

 

[becton226]

Both cards work when only one is hooked up and all four dvi ports also work. I will try the ram trick when my new psu arrives (if a new psu doesn't solve the problem). Thanks for all the help. I'll let everyone know what the deal is when i get this new psu in a few days! Thanks again.

 

[Mousemonkey]

When the screen goes blank, is that the point that you have tried switching DVI ports or have you just tried them when the cards are running solo?

 

[tkgclimb]

Some of the 750 boards have sli jumpers make sure those are set to sli, also in the bios you have to set it to some setting (different for all motherboards consult the manual) then when you load up a little icon appears I think in the bottom right of your screen and you have to enable SlI on that, for more information of setting up SLI go to the Nvidia page for it. I think the PSU is fine, it has plenty of AMPS and watts (if your's is the same antec 750w I"m looking at, then it has 25 amps on each of the 4 12v rails, and a 9800gtx+ only requires 26 (?)