Re: Memory confusion - P5WD2

In article <3WR6f.945$0V6.175@trndny06>, "DCIFRTHS" <DCIFRTHS@xxxxxxxxxxx>
wrote:

> Paul,
>
> I am registered at JEDEC, but I obviously missed this document. Nice find.
> So at least DDR2 800 is a standard!
>
> The Crucial FAQ directly contradicts what the reps I spoke to said. I am
> also wondering how old the document is because it says that there are two
> sets of timings listed for the Ballistix modules. Currently, there is only
> one set of timings posted, on the site, for their current modules. I wonder
> if they have changed their thinking on programming the SPD? Any Ballistix
> owners out there?
>
> You are correct regarding the chipset. It officially supports up to DDR2
> 667. However, the Asus site claims "native" DDR2 800 support. See quote
> below:
>
> "Native DDR2 800 Support
> To attain top performance, ASUS engineers successfully unleashed the true
> potential of DDR2 memory. Native DDR2 800 maximizes system performance by
> eliminating the bottleneck when overclocking both the CPU and memory,
> providing great performance for 3D graphics and other memory demanding
> applications."
>
> Asus may be using the "unpublished" multipliers you spoke to.
>
> Question: Will I be able to manually adjust the BIOS to run my modules to a
> slower speed, let's say, DDR2 667?

I downloaded a DDR2 data*** from Micron (126 pages!) and the
clock period for the fastest chip ranges from 3ns to 8ns.
3ns is 333MHz input clock (DDR2-667 rate). 8ns is 125MHz, which
gives less than DDR2-400 rate, meaning that DDR2, like DDR, is
backward compatible with lower rates and downward-adjustable.

Paul

>
>
> "Paul" <nospam@xxxxxxxxxx> wrote in message
> news:nospam-2310050451360001@xxxxxxxxxxxxxxxx
> > In article <7VF6f.3313$%A1.2424@trndny01>, "DCIFRTHS"
> > <DCIFRTHS@xxxxxxxxxxx> wrote:
> >
> >> 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 data***, 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
> >
> >> "Paul" <nospam@xxxxxxxxxx> wrote in message
> >> news:nospam-2210052237550001@xxxxxxxxxxxxxxxx
> >> > In article <JkA6f.1348$c%.952@trndny02>, "DCIFRTHS"
> >> > <DCIFRTHS@xxxxxxxxxxx>
> >> > 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
.

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