Dan3 <One last comment on rambus - then I promise I'll stop>
No, no, please continue. I only want to comment
on unfair terminology. When you are referring to
RAMBUS, you are saying "800MHz", while when talking
about DDR SDRAM, the numbers usually are much
lower - 200 and 266.
For an unsophisticated investor (I don't want
to point fingers here, we all know them:),
the 800 sure sounds better than 200.
However, the theoretical Rambus bandwidth is
800x2=1.6 GBytes/s while one SDRAM DIMM has
200x8bytes = also 1.6GBytes/s,
and 266x8=2.1GB/s. And we do not talk yet
about typical 4-way interleaving in servers
as you commented in your post. Therefore, I
would encourage you to find a way to always
stress this simple advantage when discussing
RAMBUS vs.SDRAM, just to remind them :)
On another note, the current cheap PC-100 SDRAM has
a bandwidth of 800MB/s. However, if you try
to measure an actual memory bandwidth in a
Pentium-XXX system (using, for example, famous
STREAM benchmark by Dr. J.McCalpin
reality.sgi.com ),
the typical Pentium-II
bandwidth will not exceed 350MB/s, or about
half of the theoretically available memory
bandwidth:
cs.virginia.edu
Why? Because apparently the Intel CPU/bus cannot provide
an adequate data flow due to internal design limitations.
Remeber someone was talking about severe memory
bottlenecks on these SI threads?
Regards,
- Ali |
