I dont understand why would you use,
1D+1E
2D+1E, since you said only enable for all data wires, instead you could use
4D+1E and send more data in same time and increase throughput, if at all it is your requirement.
> You said two clocks are same, does that mean they are coming from the same oscillator or how?. How do you say it is same clock while it is two physical boards?.
> If it is from same osciallator, then just add offset constraint to adjust the incoming signal phase and it is all done.
But instead....
Sending clocks is one way, but when it comes to high speed, it will cause too much skew. You have to either use some clock recovery mechanisms like Manchester endocing or 8b\10b encoding. I've done manchester encoding upto speeds of 20MHz between two Virtex -4 board for an optical fibre system. It worked perfect, with wire lenght < 1 feet. I'd recommend such mechanism to be used instead of wasting time in SSD or others until you really need that.