"DCIFRTHS" said:
Paul,
The information you provided to me confirms my original posting. Anything
above DDR 667 is considered overclocking.
The modules in question are Crucial Ballistix modules. The specs are here
http://www.crucial.com/store/partspecs.Asp?IMODULE=BL2KIT12864AA804
I specifically asked Crucial what the SPD was programmed to, and they
insisted (more than one rep confirmed this) that it was set to the
timings
listed in the link above (4-4-4-12). This seems rather strange to me. If
anyone is using Ballistix modules and can confirm the part number they
have,
and what the SPD is programmed to, I would greatly appreciate it.
I also searched for the standard JEDEC timings, but couldn't find them.
Kingston and Corsair have some information, but they seem to differ on
what
the standard is. I am total agreement that the SPD should be set to JEDEC
standards.
I don't think this document is going to help matters - I was really
surprised to find that JEDEC has put this in the free download
catagory. PDF page 74 has some classifications for the memory -
800's come in 4's, 5's, and 6's , 667's in 4's and 5's, both 400's
and 533's come in 3's and 4's.
http://www.jedec.org/download/search/JESD79-2B.pdf
I had to register to use the search engine, but if you are lucky,
the document will download for you without further hassle.
Now, let's review the situation on your motherboard again. Say
that JEDEC is actually allowing DDR2-800, according to that Jan. 2005
document above. In the BIOS, Asus can still consider the use of the
divider that gives DDR2-800, to be non-standard, which means even
if the top timing in the SPD is for DDR2-800, the BIOS is still under
no obligation to go there immediately. I just looked in the Intel
955X chipset datasheet, and DDR2-667 is considered to be the top speed.
That could mean, that the dividers used to get the higher memory
clocks are undocumented or unsupported by Intel. (I didn't read
the whole doc. My past experience is, Intel is not completely
honest about what dividers are available.)
PDF page 20 has a strange statement. And there is no elaboration
later. It says DDR2-667 4-4-4 is not supported ? I wonder what
the hell that means. They don't make datasheets the way they
used to...
http://download.intel.com/design/chipsets/datashts/30682801.pdf
I looked in the Crucial FAQ database and found this:
http://www.crucial.com/kb/answer.asp?qid=4050
"The specs for your DDR2 Ballistix products have two values
listed. One is a "validated" value, while the other is an "SPD"
value. Why are these different?
The memory timings listed as the validated values are the timings
that we actually test our Ballistix products to. The timings
listed as SPD settings are the values that are programmed into
the module's SPD. Your system's BIOS will often use these values
as the default for your memory settings.
The timing values in the SPD are not set as aggressively as the
ones used in our test flow because many systems are not capable
of running at these tighter timing settings. By programming less
aggressive values into the SPD, we are able to maximize the
number of platforms that DDR2 Ballistix products will work with
right out of the box.
To operate at the published validated timing specifications, you
may need to manually set these parameters in your BIOS. Consult
your motherboard manufacturer's documentation for detailed
information on how to change these settings."
They said it better than I could
Paul
<
[email protected]>
wrote:
Hi,
The chipset on this motherboard officially supports DDR2 667 as the
fastest
memory. Asus describes this motherboard as natively supporting DDR2
800.
Can
someone explain, if the memory controller supports up to 667, how the
board
natively supports the 800 speed?
Additionally, if I plug in a DDR2 800 module that has the SPD set at
2.1V
with timings of 4-4-4-12, will the board recognize this module, and
overclock the memory bus to run it at those speeds, or will run it at
slower
speed by default?
Thanks for any insight to this situation!
From the manual:
*******
DRAM Frequency [Auto]
Allows you to set the DDR operating frequency.
Configuration options: [Auto] [DDR2-400MHz] [DDR2-533MHz]
[DDR2-667MHz] [DDR2-800MHz] [DDR2-711MHz] [DDR2-889MHz]
[DDR2-1067MHz]
Available DRAM frequency options in various FSB settings
FSB Configuration options
Auto DDR2- DDR2- DDR2- DDR2- DDR2- DDR2- DDR2-
400 533 667 711* 800* 889* 1067*
FSB 1066 ? ? ? ? ? ? ? ?
FSB 800 ? ? ? ? ?
FSB 533 ? ? ?
* Provided for overclocking purpose only.
*******
The SPD EEPROM chip on a DIMM, is only supposed to be programmed
with JEDEC approved information. This aids compatibility, in
that a BIOS only need know how to parse the expected JEDEC
values. I cannot find a reference to what JEDEC currently
approves, and if the max is still DDR2-667, then that is all
you should be finding programmed into the SPD.
AFAIK, for overclockable modules, it is up to the user to set the
parameters to reach the maximum value. After all, you want the
computer to be able to POST first, and then try overclocking it.
If the computer failed to POST, because of some problem running
at DDR2-800, you'd be pissed.
Paul
