geforce 8800gs card won't work on K8t890 motherboard??

I've tried a geforce 8800gs card (with the newest graphics chip) and a 8800gts card with 640mb ram (first version of this card that came out) on a K8T890 motherboard (with updated bios). Neither card will work. Nothing on the screen (it's as though system won't even boot up). But, I've used an ATI 550 with no problems. All the cards are pci express. Anyone know why the geforce 8800 series card won't work??

 

make sure you plug in the pciexpress power connector to the video card....it's a 6pin connector like this:
http://www.playtool.com/pages/psuconnectors/pcie6.jpg

The pic on the right is an adaptor for a 4 pin to 6pin pciexpress.

 

If the board you are referring to is an ECS with both AGP and PCIex video slots, I just got through reading page after page of posts in other forums about how this board was falsely marketed, and that it is a big pile of :crap Now, this isn't my personal opinion; I have no opinion because I have neither seen nor used nor known anyone who seen or used this board. But if even a third of what I read is true, you may think about getting a new motherboard (that ECS model is pretty much obsolete now anyhow).

 

Well, I'm certainly unimpressed with this mb. Of course I did plug in the power connector (the six pin from the psu and even tired the connector that uses 2 of the 4 pin connectors to one 6 pin. Nothing I've tried has made the 8800gs or 8800gts work with this mb. Tonight my son in law is bringing over a geforce 7900gs to see if that works. I'll let ya know.