Additional DDR2 RAM

[jujubee]

Hi. I have 2 gigs of DDR2 PC3200 RAM currently. I was thinking of upgrading the other two slots with an additional 2 gigs of memory.

DDR runs in pairs and due to timing, runs best when a pair is matched (same manufacturer and type.) But do the other two slots need to be the same type of RAM as well? Id imagine since you often see timing in the advanced properties of a motherboard's settings, that this is primarily motherboard controlled and may not run at optimum bus speeds.

Anyone know if this is correct?

[mike.edel]

it might run slower anyway - if you run 4 modules you need slower timings (at least if your current modules run very fast timings)

but memory timings have only limited influence on system performance - i once read that cs2 vs cs3 is about 5%

so if you need the memory, get it

preferably matched pairs, ideally the same manufacturer as the first two ones
depending on the board you might have to specify your timings manually afterwards (for most of those overclocking modules you have to do it anyway as their spd-set timings conform to the slow standards for modules)

i am running 2 x 512 corsair valueselect + 2 x 512 infineon over here (still ddr1 at 333 fsb)

btw: in order to use dual channel you need to have modules of the same size and no double-sided modules

[RErender]

the 5% is memory performance hit not overall system performance, right?

[mike.edel]

they were talking overall system performance - depending on the application of course (memory intensive ones are likely to take such a hit while purely cpu-intense ones wont suffer)

if you run into swapping because of low memory the hit will be way larger

[RErender]

cool, I guess that makes sense since the memory is actually 33% faster, never really realized it made that much difference.

[DaForce]

if your talking about your X2 juju, then your running DDR not DDR2 ram, at the moment only Intel supports DDR2

And i have run cas2 and cas3 I honestly dont think it would make 5% system performance lose.. sounds like BS to me.
As the main driving force behind a computer is the CPU which is still the same as it was.

[mike.edel]

as i said, it heavily depends on the task at hand

if you are constantly shoving data around the ram the penalty might be big.
the pure memory transfer rate decreases quite a bit when going from cs2 down to cs3
you can test that using memtest plus as it shows you the raw memory data rate at your current latency settings
i had to run it quite often because i had a broken memory module that was causing heavy instability

the tests definetely took longer with lower latency
that said, this was an extreme case as only memory transfers were going on

ps: i can recommend memtest plus as a memory checking tool
i use it regularly, especially with new modules - faulty ones can be pretty unnerving - it is also good at testing your latency settings as too fast latencies tend to produce errors that can be difficult to identify
open source, comes with disk images and as a dos application (runs from usb dongles)
www.memtest.org

[RErender]

Interesting article on timing and clockspeed http://www.tomshardware.com/2006/03/...ies/index.html