vmknoppix
 

does vmknoppix fully load to ram and the dvd would be remove once boot to the desktop?

"VMKnoppix is Debian and KNOPPIX-based Linux live CD/DVD featuring a collection of Virtual Machine software, such as Xen, KVM, VirtualBox, QEMU, KQEMU (QEMU with accelerator) and UserMode Linux. The system enables to boot several popular distributions, including CentOS, Debian GNU/Linux and Ubuntu, in a virtual environment."

Normal Knoppix has an option to boot to ram if you in fact have a huge amount of ram it may work.

Site isn't up right now for me at least. Looks like it is hosted in Japan and they may be busy or worse right now.

the dvd is > 3gb and does vmknoppix load the 3gb to ram?

I'd guess any "toram" option would use more. Almost all new disks use a compressed filesystem and they need some extra working room.

Why do you need to run it from ram?

speedy and the dvd do not have to put on the dvd rom

Option is to see if you can create a live usb.