So i checked out AMD RamDisk today. I made a 4gig drive becuase the free version only allows that much. My RAM setup is 16gigs of Crucial Ballistix Sport 8GB 240-Pin DDR3 SDRAM DDR3 1600. And these are my CrystalDiskMark 3.0.2 x64 test results.
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CrystalDiskMark 3.0.2 x64 (C) 2007-2013 hiyohiyo
Crystal Dew World : http://crystalmark.info/
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* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]
Sequential Read : 3317.173 MB/s
Sequential Write : 3462.933 MB/s
Random Read 512KB : 3199.134 MB/s
Random Write 512KB : 3337.490 MB/s
Random Read 4KB (QD=1) : 331.008 MB/s [ 80812.4 IOPS]
Random Write 4KB (QD=1) : 286.324 MB/s [ 69903.4 IOPS]
Random Read 4KB (QD=32) : 327.930 MB/s [ 80060.9 IOPS]
Random Write 4KB (QD=32) : 264.283 MB/s [ 64522.2 IOPS]
Test : 500 MB [E: 0.0% (0.0/4084.0 MB)] (x5)
Date : 2013/07/02 13:23:31
OS : Windows 7 Professional SP1 [6.1 Build 7601] (x64)
Back in DOS days I used to use RAM drive and always knew it would take off one day but now with SSD's and the hassle I never used it for more than a few weeks but its a great idea. Maybe when I have a bit more time I will give it another go.
RAMdisks are of limited use on Windows, usually, unless you're willing to put up with some extra hassle, and the limits of whatever (usually not free) software you use to handle them.
On Linux, they're built into the operating system. You can just "mount" a chunk of memory as a drive, with no other software involved (this is because Linux and Windows have subtle, but important, differences in how "files" and "drives" are defined and used).
Linux also has a more useful scripting environment. You could set up a script to, say, automagically create a RAMdisk and copy a game's files to it, then run the game from memory. Or you could use scripts to emulate how a RAMdisk generally works in Windows (OS starts, RAMdisk autoloads contents to memory, profit), or even the special features of the AMD RAMdisk software (only saving the files that are actually changed, not the whole disk, and doing it immediately, not at shutdown). Even more advanced stuff is also very possible.
And that's all free with the Linux OS, if you're willing to write some scripts. Servers and highly organized Linux environments use that sort of thing all the time. I have a 16GB memory kit on its way right now, and once it's installed, I'll definitely be playing around with RAMdisks a lot more, on both Windows and Linux.