I've been building computers off and on since they had memory in the kilobytes.   Setting forth on the newest build with 64 Gb memory, i7-5820 processor, RME HDSPe AIO sound card, windows 7 64bit.  Any helpful ideas to use all that memory ?  Mostly it will be loading a bunch of Kontakt 5 instances, plus some extras like Gplayer and UVI workstation. 

Most VSTis that run samples, do so from disk so while 64 GIG of RAM is helpful there is point of diminishing returns. There is little you can do to manually manage how memory is used. Some particular plugins allow you to allocate resources but this is usually left as automatic if the option exists.

I have a boatload of memory too, AFAICT the biggest improvement comes from turning up the disk (read caching) cache. YMMV.

Likewise.
 
The most I've ever seen Sonar consume is about 9Gb, and that's with my orchestral template/project

We'll see!   I debated getting just 32 Gb but hopefully this will keep me happy for a long time.  Also added an SSD.   Related question: with disk drives getting so huge, one doesn't use so many of them, so the old wisdom of splitting sample libraries across multiple disks doesn't seem to work.   How might one best use just two: a 500 Gb SSD and a 3 TB 7200 SATA6?   I'm thinking, since the system drivers and all will be in memory, not accessing disk, that the SSD can hold both the system and the sample libraries (on two allocated disk units so when the inevitable windows reload happens the libraries will not have to be rebuilt).   Ideas? 

I've got 16Gb I don't see myself wanting to upgrading in future. On the other hand if somebody offered me a really cheap upgrade you never know (although my motherboard is maxed out)...

Many years ago we used ramdisks to improve speed. eg: load the database indexes to a ram disk.
 
Only thing I can think of now is to point the picture cache to a ramdisk. Or, loading all samples to a ramdisk.
 
The Ramdisk utility is one of the first items loaded during startup, the ram disk is created and the disk image of that "disk" is copied to it. When the computer is shut down the contents of the ramdisk are copied to the "hard disk" for next boot.
 
Unless the computer is forever on.
 
But with the current speed of disks, computers, vid cards prolly not very useful, especially when samples are stored on and SSD.

If you plan on creating/using large orchestral templates, 64 gigs is great...The more templates I'm creating, the more I appreciate having the ram available for Kontakt...While I don't plan on upgrading for awhile, 64 or more gigs is on my next must have!  Most folks here don't seem to find this necessary, but over at V.I. Control's forum mega ram is much more appreciated as many of those folks are using large templates.  When loading these templates I can watch my ram usage get gobbled up fast. However, this is a convenience factor for me as it is much quicker to load a big template and delete what isn't used in the end than to build from ground up which would minimize memory needs...
 
Regarding samples on your SSD c drive... I also have a 500 gb and have placed my entire Spitfire Albion 1,2,3 package on it, as it is the Kontakt library I used most often with large templates.  I have my other favorite package, Project Sam's OE 1&2 on another SSD.  I've moved lesser used packages like Kirk Hunter's and EW Platinum Orchestra to conventional drives.  I would use this approach... ie, keep your favorite sample packages on the ssd.  It cuts load times tremendously/

I happen to have 32GB of memory, and never ever never have any memory-related bottlenecks, so I don't imagine you will run into any anytime soon with most reasonable approaches to projects.
 
I only load what I need, and never even come close to having to ever wonder how close I am getting on memory usage - and that's fine for me.
 
I don't know that it would ever occur to me to just load up memory because it is there :)
 
Bob Bone
 

Most motherboards that will hold 64 GB will hold 32 GB and still leave room for another 32. Given that memory is not yet free, you might want to consider populating your board with a more reasonable amount of memory, and using it for a while to see if you are experiencing any performance problems before putting in a bunch of memory that might not give you any actual benefit.