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More info?)
Rob Stow <rob.stow@sasktel.net> wrote in message news:<1078g6hcpr6e11c@corp.supernews.com>...
> Dave wrote:
>
> > I have got 768 MB of SDRAM (133 MHz) on my system.
> >
> > If I go to a DDR mobo then how much 3200 DDR-400 would I need to
> > get to roughly match the performance of the SDRAM?
>
> Depends on whether the things you do are most
> dependent on the RAM speed or the RAM quantity.
>
> If you do things like video editting, the more RAM the better,
> even if you have to settle for something a little slower than
> PC3200.
>
> If you do mostly gaming (plus trivial stuff like word processing
> and web browsing) then 512 MB of low latency PC3200 should do
> you very nicely.
As a general rule, the greater the memory bandwidth, the faster your
code will run. However, it isn't that simple. A lot will depend upon
how well your program utilizes the on-chip caches. Typically, cache
hit ratios are around 90% or better. This means that 9 times out of
10, the data or instruction that you need will be in cache. This is
independent of SDRAM or DDR memory.
Now, if you get a cache miss and have to go to memory, then you will
see the speed of memory. Or, if you are doing a lot of disk intensive
activity, the memory speed could come into play. In any case, it isn't
a 1:1 relationship between memory bandwidth and code execution speed.
arnie