I've had this problem for a long time and asked about it here.  A solution for a while was to unplug the card (literally pull it out of the server), and reboot, then put it back in, and reboot again.  For some reason this got me booted.  I had to reboot recently and the "trick" is no longer working.  Does anyone have ANY idea how to troubleshoot this?? 

 

This is on a GA-7PESH2

 

Here is a picture of the Kernel panic

I see you've tried different cards in the slot and different kernels. It could be a faulty motherboard. Is it still under warranty? Have you tried other slots? Have you cleared the CMOS? Reflashed the BIOS? Have you stripped it down and checked that there isn't a misplaced standoff shorting out something on the underside? How about blowing compressed air over it in case there's a metal filing or other debris causing a problem? Just a few suggestions that I haven't seen mentioned before. I once found a sliver of plastic - I think it was from the conductive bag - lodged in a DIMM socket.