"Dragoncarer" said:
Yep....at my parts store they list their dual channel RAM as "1GB (2x5412MB)
Brand name yadda yadda" and the price is the same as buying two individual
sticks.
<Snip>
Oh wow, thanks so much! You are a font of knowledge!
And now another couple of questions:
I have an existing stick of 512MB DDR400, and my current Mobo is an old
Gigabyte model. I plan on upgrading soon and will get an ASUS
A8N-SLI....will that existing stick of 512 work alongside a pair of 512 in
dual channel mode? Ie., I'll pop the (new) dual-channel sticks in the right
slots to enable dual-channel config, and the remaining (old) stick in a free
slot.
Second question: if I buy the two sticks of RAM now to use as dual channel
in my new Mobo when I get it, can I use those sticks in my current Mobo
(obviously they won't run in dual channel)? I'm fairly certain you've
answered this question in your previous posts: the dual-channel sticks
aren't anything special or different from normal DDR400, they're just a pair
from the 'same barrell', as you put it.
Once again, many, many thanks.
http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/26094.PDF
Ok, so I'm a (little) bit of a tech head, but this is far too tech for me,
but thanks for the thought!
The Athlon64 memory controller works with 1, 2, or 4 sticks of RAM.
One stick in B1 or B2 in single channel (B bus is the primary bus).
Two sticks in B1 and B2 as single channel.
Two matched sticks in A1&B1 as dual channel
Two matched sticks in A2&B2 as dual channel
Four sticks, using the last two combinations together.
(On Rev.E, I've just read a claim that A1 and A2 can be used in
single channel, but I'll wait until someone confirms that it
actually works, as the BIOS might not support it. Up until now,
Athlon64 wasn't fully symmetric in terms of its usage pattern, so
A1 and A2 couldn't be used in a 64 bit mode.)
Athlon64 is not true dual channel - it operates in 64 bit mode
or 128 bit mode (sort of like a "double wide" single channel).
Once you make the decision to go dual channel, via using A1&B1 or
A2&B2, a third "lonely stick" cannot reside in a third slot -
the BIOS should ignore the third stick. Up to this date, the
Athlon64 does not have the flexibility of an Nforce2 chipset,
where virtually anything is possible.
If you had mentioned your Gigabyte model number, I might have
been able to comment on what options might work there. If it
is a single channel three slot board, some typical configs:
three double sided sticks at DDR266
two double sided sticks at DDR333 (using slot 1 and slot 3)
one double sided stick at DDR400 (slot 3, furthest from CPU)
On boards that have more than one address bus, more is possible.
A S754 board has two address busses, and on those, two double
sided sticks work at DDR400 command rate 2T, using slots 1 and
3. An Nforce2 board, which has three address busses, can run
three double sided sticks at DDR400 (CAS2 memory recommended
for best results).
On the Intel chipset side of things, Intel skirted the issue,
by limiting the drive signals available to support only two double
sided DIMMs in some of the last single channel boards. Thus, those
boards were limited to two double sided sticks at DDR333 as well -
the slots you are allowed to use may differ in that case.
Intel dual channel boards can run four sticks at DDR400, as they
are really two, two stick channels. Similar to Athlon64, but
for some reason, without ever exposing the command rate setting
as an issue (there is no chipset register for command rate, and
Xbitlabs claims it always runs command rate 2T).
HTH,
Paul
