You will pay more money for a 9xxx series cpu, cooler and motherboard then any i5 or xeon setup that will be much faster.
In current games the i5 beats out anything AMD makes.
Intel cpu's have a more efficient architecture so apples to apples they perform significantly better.
Now AMD's 8XXX and 9XXX CPUs are 4 physical/8 logical core cpus so they are like an i7 or Xeon in total threads/processes. Currently only a select few games are coded to use more then 4 cores/threads so the advantage the AMD has over an i5 is irrelevant and thus the 4 stronger cores of the i5 beats it hands down.
In the future this might change and then the AMD might pull ahead of the i5 which is now more of an apples to oranges comparison. But when you match it up against a Xeon or i7 which has 8 threads as well (apples to apples), those cpu's (even with a lower clock speed) will beat the AMD.
Sorry for the long explanation but that sums up how the stack up now and in the future.