Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
In article <20041205024803.07763.00001690@mb-m01.aol.com>, caecina@aol.com
(Caecina) wrote:
> It states that it's RAM options are 'DDR2 Speeds Auto, 400, 533'.
> No mention of 667; so I assume it doesn't support it. Why are
> RAM manufacturers producing RAM which virtually no motherboards
> support?
http://www.asus.com/prog/spec.asp?m=P5AD2-E%20Premium&langs=01
Supports 533 and 711 DDR2. FSB1066 max
http://www.asus.com/prog/spec.asp?m=P5AD2%20Premium&langs=01
Supports 400 and 533 DDR2. FSB800 max.
If you download the manual for the P5AD2 Premium, it talks about
600 DDR2 via overclocking, which means you would be using
the divider for 533, but overclocking everything, to get
to 600 or so.
It you want trustworthy info, do a search on Abxzone, or
read reviews on Anandtech, to see what users and reviewers
have run into. I vaguely remember some issues with overclocking
DDR2, and I think they may have been BIOS related (something
about setting a certain speed in the BIOS, but when checked
with CPUZ, the speed wasn't there). It isn't the motherboard
manufacturers that are trying to stop this, it is Intel
that tries to spoil the fun, by inserting overclocking
limiters in their chipsets. And, Intel didn't even do a
good job of designing their limiters - as if they wanted
the motherboard manufacturers to figure it out
Try searching for P5AD2, or 925 chipset or the like.
http://www.abxzone.com/forums/search.php
Overclock limiters - Page 3 shows DDR2 overclocked memory.
Presumably this is the "DDR533" 3:4 ratio setting, then
overclocked via raising the FSB from 200 to 275, giving DDR733
memory. This is what you have to do, if Intel doesn't give
higher divider ratios. The 925XE should make this easier,
as at FSB1066 to FSB1200, and keeping the 3:4 ratio, you
should more easily be able to exceed DDR533.
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2124&P=3
This article claims a separate divider is provided for 711,
but I think it is still the same old 3:4 ratio. FSB1066
is 266MHz clock * 2 * 4/3 =approx 711. What it means instead,
is Asus found a way to make the other speeds, while at FSB1066.
In other words, there is no magic here, just the fact that
the FSB is clocked higher on this board. It begs the question
why the Abit board doesn't do the same thing. (Intel doesn't
document every detail in their datasheets, and that is why
these divider mysteries take each mobo maker time to figure
out - that could be why the feature sets don't match on
release day. Intel only feels inclined to support "JEDEC
official speeds", and that is reflected as well in how
Intel develops their own motherboards. Intel sells to
conservative corporate customers, and if you saw the sales
numbers listed on Anandtech, gamer sales are peanuts and
really not worth pursuing.)
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2124&P=3
This post seems to suggest Abit is trying. They added a
BIOS item to the AA8 (predecessor of AA8XE) for DDR600, so
it is possible the AA8XE will have additional options as well.
Probably just a matter of discovering undocumented divider
options in the Intel chipset.
http://www.abxzone.com/forums/showthread.php?p=846642&postcount=56
Further along in that thread, is mention of a 2:3 divider, and
I guess that is how Abit gets DDR2-600 at stock speed ==>
200MHz clock * 2 (for DDR) * 3/2 = DDR2-600
Try downloading the Abit manuals for the AA8 and AA8XE and
see if the memory dividers are documented. Maybe your problem
is already solved, to some degree.
This article mentions that DDR2-667 is a standard, so at
some point Intel will officially support it.
http://www.tomshardware.com/motherboard/20040719/intel_925xe-02.html
HTH,
Paul
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