RAM questions

I see that Dell offers dual channel DDR2 SDRAM at 667 MHz and 800
Mhz. The 800 MHz RAM is a little more expensive than the 667 MHz
RAM. Will the 800 MHz RAM offer better performance with all CPUs? Or
could the 667 MHz RAM be better for certain CPUs?

Also, if you want 3 GB of RAM, why does Dell say they will install 4
DIMMs? I assume they will put in two 1 GB DIMMs, and two 512 MB
DIMMs? I also assume there are 4 DIMM slots, so that means you can't
upgrade to 4 GB later. Why don't they just put in three 1 GB DIMMs?

<> wrote in message
news:7008bf54-f19c-41be-afe9-...
>I see that Dell offers dual channel DDR2 SDRAM at 667 MHz and 800
> Mhz. The 800 MHz RAM is a little more expensive than the 667 MHz
> RAM. Will the 800 MHz RAM offer better performance with all CPUs? Or
> could the 667 MHz RAM be better for certain CPUs?
>
> Also, if you want 3 GB of RAM, why does Dell say they will install 4
> DIMMs? I assume they will put in two 1 GB DIMMs, and two 512 MB
> DIMMs? I also assume there are 4 DIMM slots, so that means you can't
> upgrade to 4 GB later. Why don't they just put in three 1 GB DIMMs?
>


On desktops with (4) DIMM sockets, yes, there are 2x1GB DIMMs + 2x512mb
DIMMs = 3GB

Laptops only have (2) DIMM sockets, so it would be (1) 2GB DIMM + (1) 1GB
DIMM = 3GB

"S.Lewis" <> wrote in message
news:lzmRj.68092$.. .
>
> <> wrote in message
> news:7008bf54-f19c-41be-afe9-...
<snip>
.. Why don't they just put in three 1 GB DIMMs?
>>
>
>
> On desktops with (4) DIMM sockets, yes, there are 2x1GB DIMMs + 2x512mb
> DIMMs = 3GB
>
the reason they dont put 3 x1gb dims in is because they are interleaved, and
so with the 2x1GB DIMMs + 2x512mb configuration it is faster than 3x1Gb

Hi!

> Will the 800 MHz RAM offer better performance with all CPUs?

Not necessarily. Some CPUs will work optimally with the slower memory.
Look at the front side bus speed of the processor to know which RAM
you should get.

> Also, if you want 3 GB of RAM, why does Dell say they will
> install 4 DIMMs? I assume they will put in two 1 GB DIMMs,
> and two 512 MB DIMMs?

> Why don't they just put in three 1 GB DIMMs?

Some memory controllers work faster (or even more reliably) when
memory can be interleaved. This requires that at least two matched
DIMMs per bank (two sockets) be installed. However, it has been shown
that on some systems, interleaving makes very little (or sometimes no)
difference in performance.

William

On Apr 28, 3:12*pm, wm_wa...@hotmail.com wrote:
> Hi!
>
> > Will the 800 MHz RAM offer better performance with all CPUs?
>
> Not necessarily. Some CPUs will work optimally with the slower memory.
> Look at the front side bus speed of the processor to know which RAM
> you should get.

So basically if the FSB is a multiple of the RAM speed, then that is
the best situation? So if the FSB is 1333 MHz, then you should get
667 MHz RAM? What if I want the Q6600, which has a FSB of 1066 MHz?
Dell only sells 667 and 800 MHz RAM.


> > Also, if you want 3 GB of RAM, why does Dell say they will
> > install 4 DIMMs? *I assume they will put in two 1 GB DIMMs,
> > and two 512 MB DIMMs?
> > Why don't they just put in three 1 GB DIMMs?
>
> Some memory controllers work faster (or even more reliably) when
> memory can be interleaved. This requires that at least two matched
> DIMMs per bank (two sockets) be installed. However, it has been shown
> that on some systems, interleaving makes very little (or sometimes no)
> difference in performance.

I guess if I'm getting a 32 bit OS, then 3 GB will be almost the
maximum amount that the OS can recognize, so there won't be any point
in upgrading to 4 GB later (unless I were to upgrade to a 64 bit OS
later).