Question about D90D7/D90D7P

Question about D90D7/D90D7P

Our organization has several D90D7's in production. They all have 16GB of flash storage, and 4GB of memory. My while researching an issue, I happen to notice that there is also a D90D7P model, which uses a version of WES that utilizes x64 architecture.....therefore utilizing all 4GB of memory.

My question is: What is the point of the D90D7's having 4GB of memory if the OS won't recognize anything over 3GB?

I tried loading the D90D7P image onto the D90D7 using the USB tool, but alas...I got a security key error.

Thoughts?