The first important parameter is energy efficiency. Namely we are talking here about the significant power losses as a result of numerous conversions that take place inside of the system PSU. That is why Intel considered a simple but efficient modification of the contemporary power supply for datacenters to be quite handy:
The typical datacenter power system is delivering only a third of the power. The problem is that there are too many conversions, that’s where the efficiency is lost.
The new type of PSU uses different conversion scheme, and as we can see from the picture below the advantages of the DC power vs AC power are evident:
We can get 60% per megawatt improvement: