Hello,


I'm in the process of building a new system with an Athlon X2
5600+, I'm running into an issue with the memory that I need. The
motherboard that I'm looking to purchase can support up to DDR2 800.
When I built my old Athlon 2100 system 4 years ago, even though my
motherboard supported DDR 2700 memory, the processor only supported up
to 2100 memory. I've looked at some places and they had mentioned that
the 5600+ can run on DDR2 667. I'm not planning on overclocking at
all, so if I were to purchase the DDR2 800 with this processor, will
it only work at DD2 667 or will it utilize the faster DDR2 800? Is
there any site out there that could help in determining what memory is
needed for what processor?

One other question, is the CAS 5 vs. CAS 4 a noticable difference?


Thanks in advance for the help

Nick

On Thu, 17 May 2007 11:00:35 -0400, Nick thoughfully wrote:

I hear you but why risk it? Better to use DDR2 800 and not get bogged
down with memory errors later.

I also understand what you are saying, but isn't a processor made to
handle only one default bus speed, or has this changed?

Nick

On Thu, 17 May 2007 23:04:19 GMT, jaster <jaster (AT) home (DOT) net> wrote:

A few points:
The speed rating of RAM is its maximum capable speed (at which it passed
manufacturers tests). You can run it at a slower MHz and it may even run
with faster timings (cas etc).

I think with your old athlon setup, the motherboard probably didn't offer a
memory speed faster than the FSB of the processor. With a 266FSB (133MHz)
processor like the Athlon 2100+, the motherboard limited the memory speed of
the RAM to 266. Had you installed a faster FSB processor, then the
motherboard would have allowed memory speeds to match.

It is the motherboard (set in the BIOS), not the processor that determines
the memory speed. If your motherboard can take DDR2-800, then I would
suggest buying just that. The FSB of the processor is a different figure
(that may or may not match RAM speed).

On Thu, 17 May 2007 19:21:24 -0400, Nick thoughfully wrote:

IIUC, processors can handle faster or slower memory speeds or bus speeds,
ie, overclocking, and even mixed memory speeds. Memory operates at the
speed of the slowest memory. Some memory although rated slower may
actually run at higher speeds.

Bottom line the cpu and m/b should run with slower memory but probably at
less than optimal overall performance. Most cases you might notice a
differences depending on the applications you're using, such as, video
encoding, CAD, 3D gaming. Truthfully you won't notice any difference
except in performance comparasion charts like 3DMarks and Sysoft.