Power of Big-Mem Kernel

I found some difference between normal kernel and big-mem kernel.

The normal 2.6.32 kernel Version or above, supports RAM upto 3GB only(I Guess).
My System RAM is 16 GB.

First I installed Boss Advanced Server 1.0 in the System and I think
the kernel version is 2.6.32 kernel.
After that I installed Big-Mem Kernel and I restarted the machine.
After GRUB was loaded, I found the entry  for the bigmem kernel.
I booted the machine in the big mem kernel and I checked the RAM availability.
Wow,!! I was able to see that 15 GB RAM has been detected.