Dell 690, PCI-X Card & 2nd Processor make led 1 & 3 blink

Dear All,

I'm writing you because I'm in trouble since a week with my Dell Precision 690 (2x Xeon DP 5080, Motherboard 0MY171, Bios A8, 750W PSU).

I'm willing to install a SCSI Card (Adaptec ASC-39320A/DELL, pci-x) to connect an old film scanner. It works fine with 1 CPU (in socket 0). But when I insert the 2nd one (in socket 1), it can't start anymore. I get led 1 & 3 blinking. Same when I trying with 1 CPU in socket 1 (and socket 0 empty). Else, it's working perfectly fine with 2 cpu and no SCSI card.

To "acknowledge the fault", I have to remove both the processor in socket 1 and the card. Removing only the card doesn't have effect on the "won't boot/led blinking issue". 

I read that led code 1 & 3 might be a PSU Issue. So I tried with another power supply, but it still the same. Removing the coin cell battery to clear the CMOS : no effect. I upgraded the bios to A8 version, still no effet.

I'm a bit lost, I'm running out of Idea. Could you help me if you can ?
Any help would be great help :)