I got a new dual Crosshair memory pair. The exact same as the dual pair that was already inside (Speed, Size etc). But after installing. The PC mostly didnt boot up, the creen would get no signal, and sometimes it booted till the bios screen and than froze.

Configurations
Dimm A1 OLD Dimm B1 OLD
Dimm A2 NEW Dimm B2 New
and vice versa. No sucess

Each pair using by its own. The PC boots without any problems.
I took a even closer look an the RAM and on the new one was written V1.71
while my other pair is V1.51

Than I tried:

Dimm A1 NEW Dimm A2 New
Dimm B1 Old Dimm B2 Old
Now the PC starts fine and without any problems.

My question here is:
Im a bit concerned if this setting is right or not. If it can harm the Board, memory etc. Or if it is supposed to be like this.

TXS

You might try raising the DIMM voltage by .1V when you have two modules in. After raising the voltage, then try 4 modules.