Wait, something is strange

I use the i486 version of plop.
And it see's "only" 1942196kb of RAM.
Why?
If it has only <2GB, and the rootfs is 1.6GB -> no wonder that it does not work!
But i ask me why is the rootfs 1.6GB when booting from USB and only 932MB from PXE?

Maybe because of the customized initrd?