Windows 7 (x64) memory usage climbs to 90%+ while system is idle?

Solution 1:

It's only a problem if that memory is unavailable for other tasks when called on. Just because it's used now doesn't mean can't be released quickly when needed, and in fact leaving the memory unused would be the real waste.

As a side note, this is another difference in the way that Windows and Linux use memory. On a linux system, this would be a little more worrying because swap is just used as a last resort. Nothing is swapped unless absolutely necessary, and so Linux would have to first take the time to write used RAM to the swap partition before it could be reclaimed for other programs. Windows, on the other hand, likes to keep all RAM paged all the time. This way, if it needs to use RAM to use for another process it is already paged to disk, and so it can be reclaimed much more quickly. It's a tradeoff - Linux is faster in this respect for RAM that will never be paged/swapped, and Windows is faster in this respect for those times when you need to swap quickly.

Solution 2:

Disable the sidebar process. It's known to leak a lot of memory (although it's more likely the add-ons that it hosts that are probably causing the resource leaks).

Suggestion: Upgrading to 8 GBs of RAM is better if your motherboard can support this since Windows Vista and Windows 7 both do consume a lot of memory, and the newer applications also seem to be using more RAM these days as well.