Resources at Idle Double when Upgrading RAM Capacity

[Z15CAM]

[FONT=&quot]I’ve been an avid Fan of AnandTech since the early 90’s when he 1st uploaded.

I’m also a Computer Nerd from the days of DOS and Card Punch.

I know this Post may be saturated with Days of Yore using Socket A as an example; but, one thing has always Nagged me over the years when upgrading RAM Capacity: Say DDR of approx the same Latency with twice the capacity… eg: 2 x’s 512=1G 2-2-2-5 1T @ 400MHz to say 2 x’s 1G=2G 2.3.2.5 1T @ 400MHz on say an EpoX 8RDR3+ or a GA-N7400 Pro2 (Rev2) [nForce2 Ultra MB`s in this case] and here in Lies the Rub ;o)

EG: Both MB’s run Win7 Idling at 280Mb’s of Physical Memory with 2 x’s 512=1G 2-2-2-5 1T @ 400Mhz with a Barton running at 2.2 Mhz’s; but, both MB`s IDLE at 450Mb`s with 2 x’s 1G=2G 2.3.2.5 1T @ 400Mhz. I see very little discrepancy in Paging between the 2 scenarios. Granted 2G`s Dual Channel DDR is much smoother and handle Loads faster. Considering everything but the RAM Capacity is Identical, why would the Hardware NOT Idle the OS with the same amount of resources used that is 280 Mb’s?

I don’t know if you have observed this as I have over the years when upgrading Ram Capacity and have never understood why the OS would use more resources when doubling the Capacity of Physical Memory.

Other then the Observation there is no Problem except WHY ;o)[/FONT]

 

[Emulex]

why not? unless you specifically told the o/s not to use the ram or have balloons to put pressure on ram usage this is how the o/s id designed to work.

 

[Ben90]

Welcome to the forums, and good question.

Programs, including operating systems use a different amount of RAM depending on how much is available. This phenomenon you noticed. The reason for this is because not all stored information is completely necessary for program operation. A lot of it is used as caching to improve program responsiveness.

The biggest eater of empty RAM on Windows 7 systems is Superfetch. This technology caches your highly used programs which allows them to load up faster as they don't need to retrieve quite as much from the hard drive. So even if you have no programs currently open, Windows 7 has information required to load your browser stored in RAM. Quite useful for those of us who still rely on those slow spindle drives.

There are other scenarios where more RAM than required is being used for performance reasons, these are all good things. The less the HDD needs to be used, the better.

Once you load up a program that really needs RAM, such as Linpack or Photoshop, the memory manager in Windows will start throwing non-vital information such as Superfetch or the excess buffer on your MP3 player aside to make room for Photoshop.

 

[Z15CAM]

Thanks Ben for your time and comprehensive answer.

From your answer I take it that Win7's Superfetch loads DLL's into Ram for Programs that are most commonly used and the Volume of Ram Allocated for Programs is determined by the OS capability to recognize the Total amount of Ram, in this case Doubling the Capacity: hence, the Volume DLL's loaded into Ram is more or less Doubled thus the OS Idles much Higher and more Efficient.

 

[taltamir]

Windows recognizes that it is ram starved and disables features automatically to reduce ram consumption at idle. I recommend at least 4GB of ram for modern OS & programs in the year 2010.

Superfetch is not actually related to that, superfetch fills ALL "unused" ram with most frequently used data, since discarding it is near instantaneous it does not impede performance at all when requiring more ram, while greatly improving HDD access performance, all the ram used by superfetch is listed as available by windows.

that is, if your system shows 500MB in use out of 2000MB of ram, then 500MB is used by windows and programs, and 1500MB is used by superfetch, should you load a program and it will ask for 200MB out of the "available ram" superfetch will instantly discard 200MB of the cached data and give that program its 200MB, so that you will have 700MB in use and 1300 available space that is actually being used by superfetch.

Note though that in the task manager win7 will actually show in use (graph with number underneath), "available", and "free", where "available" is the ram used by superfetch... programs see it as "free space"

Superfetch is the CORRECT way to utilize ram, and is the best thing to ever come out of MS.