What to put on RAMDisk on Windows?
Solution 1:
"What to put on RAMDisk on Windows?" A: Nothing.
A RAMdisk is a foolish use of RAM.*
Windows, esp in Vista and later, will do a perfectly good job of using "extra" RAM for file and page cache. It does this completely automatically. And if a process suddenly turns out to need that some of that RAM-that-once-was-"extra", the OS can take it back from these caches just about instantly (only marginally slower than when it uses "free" RAM) and let the process that needs it, use it. It will do so intelligently, first repurposing low-priority cache that hasn't been accessed in a long time.
Whereas... When you lock RAM away in a RAMdisk the OS then can't ever use it for actual "live" contents (i.e. to resolve page faults), not in any amount of time. That's bad.
Practically all claims that "the OS isn't managing my RAM well" are due to misinformation about how virtual memory works and what it does, and misinterpretations of various displays. (Granted, Microsoft has not helped much here.)
(* The only exception I'll agree to is if you're running e.g. 32-bit Windows clients, which just won't look at more than about 3 GB of RAM. A RAMdisk product that makes use of RAM the OS flatly can't or won't use doesn't take anything away from the OS. A better long-term answer is of course to go to an OS that will use of all of your RAM.)
Solution 2:
Basically, anything that you need speed for, that you will use often. Its a way of increasing your apparent ram.
More info here: http://www.techrepublic.com/blog/window-on-windows/how-do-i-use-a-ram-disk-to-help-speed-up-disk-intensive-applications/3430