System Performance with 3, 6, or 12 G of RAM

[LenS]

Tom's just came out with this report on the performance difference varying amounts of RAM have on an overclocked Intel Core i7 920 system. Short answer not much. The only real difference was in power consumption, with the 3Gig system, unsurprisingly, using 10-20% less. The other tests showed less than 1% difference.

The tests were run on Vista and hence may not be completely applicable to Linux, but still provide some interesting data. It would be interesting to see if Linux behaves differently, (hint, hint), also if using an AMD processor changes the results. I don't think it would but...

Source: Do You Really Need More Than 6 GB Of RAM? : Is “Too Much” Really Just Enough? - Review Tom's Hardware
Address : <http://www.tomshardware.com/reviews/memory-module-upgrade,2264.html>Do You Really Need More Than 6 GB Of RAM?

Len

[RealNC]

The performance difference is *immense* when you actually do something that needs that much RAM. For example having a big matrix in Matlab. If it's 12GB big but you have only 3GB RAM, you would wait *months* for the result.

[deanjo]

Ya, maya can chew up the ram in a heartbeat as well. For the average Joe though at this time massive ram amounts won't do much for them.

[LenS]

Yeah, there are certainly apps that can use a lot of memory. Protein folding and climate modeling are another two that come to mind. But as deanjo says for the average user huge amounts of ram are useless. Tom ran some tests with several apps running: video encoding (divx), file transfers, and gaming, with 100 windows in IE open, again no advantage in having over 3G.

Those tests use 3 channels of DDR3. It would be interesting to see if using 2,4, or 8G of DDR2 affects performance any.

Len

[deanjo]

Just thought I would ad that Tom's likes to "interpolate" results. So always take their results with a gain of salt especially when they are talking about scaling of anything.

We caught them fudging in the openSSL test when they updated their CPU charts.

http://www.tomshardware.com/charts/desktop-cpu-charts-q3-2008/Linux-OpenSSL,844.html

That is one test that the AMD's walk all over the intels but yet they are the only ones that show otherwise. (BTW they used PTS for those results and when confronted they admitted to extrapolating the results based on other tests)

[LenS]

Just thought I would ad that Tom's likes to "interpolate" results. So always take their results with a gain of salt especially when they are talking about scaling of anything.

We caught them fudging in the openSSL test when they updated their CPU charts.

http://www.tomshardware.com/charts/desktop-cpu-charts-q3-2008/Linux-OpenSSL,844.html

That is one test that the AMD's walk all over the intels but yet they are the only ones that show otherwise. (BTW they used PTS for those results and when confronted they admitted to extrapolating the results based on other tests)

Thanks, that;s good to know. I guess it's much easier to interpolate than actually run the tests. They couldn't get memory modules in 1,2, & 4G sizes running at the same stock speed or from the same manufacturer so they changed the settings in BIOS to match the speeds.

It's pretty much a given in science that results need to be replicable before being accepted. I remember the unbelievable "discovery" of cold fusion a few years ago. It turned out to be just that, unbelievable.

Len

[a7v-user]

As soon as there's more 64bit games coming out you'll see more games benefitting from 8 or 12 GB ram. Right now they're shoe-horned into the 2GB available to 32bit applications.

[RealNC]

Actually (but don't take this for granted, I could be wrong), 32-bit games on 64-bit Windows (the main gaming platform for PCs) can use 4GBs of RAM because the kernel address space can move outside the game's address space, leaving the whole of the 4GB addressable memory for the exclusive use of the game.

[AdrenalineJunky]

Actually (but don't take this for granted, I could be wrong), 32-bit games on 64-bit Windows (the main gaming platform for PCs) can use 4GBs of RAM because the kernel address space can move outside the game's address space, leaving the whole of the 4GB addressable memory for the exclusive use of the game.

thats true, but there is a bit more to the story.

http://msdn.microsoft.com/en-us/library/aa366778(VS.85).aspx

that said, i still wouldn't expect more 64 bit games would mean that more games would benefit from the increase in ram - i just wouldn't expect them to need that much memory space. certianly games will get to that point sometime in the future, but speaking in terms of present day gaming i doubt you'd find a game that would gain much even if they specifically coded it in a way to use as much ram to speed up performance as they possibly could.

edit: so i did a little more reading on the subject and came across a crysis hardware guide from gamespot that shows absolutely no performance difference between 1, 2, or 3 gigs of ram.

http://www.gamespot.com/features/6182806/p-6.html

[ldesnogu]

Even if you don't need all of your RAM for your applications, the kernel will use as much as it can for file caching.
For developers that can make a big difference (think of header files).

I have no application that needs a lot of memory but I'm glad I bought 6 GB, my HD is almost useless :)
OTOH I wouldn't need 12 GB but some other devs might think differently (doesn't Eclipse use big amounts of RAM?).