1023 MB is 1 GB. Thats not enough room for most games and maybe 100 small mp3's.
A ram disk is a software disk created by using avaliable RAM which is what makes it superfast; it has nothing to do with the free space on your harddrives.
You can allocate the size in the Software that you are using to create it. I would not exceed 8Gb since you only have 12GB in your system.
This allotment subtracts from the total ram so you would be leaving windows, app, games to run on just 4gb if you made an 8gb ramdisk.