I have an A7N8X-Deluxe Rev.2 board. I'm using two 512MB sticks of
Kingston value ram DDR2700 and Running FreeBSD-4.11RELEASE-p9. If I use
the two sticks in slots 1 and 2 things are fine; _no_ stability issues
whatsoever. But if I move the stick from slot 2 to the slightly more
distant slot 3 to get the dual channel bit I'm plagued with spontaneous
random reboots.
Does using this (1 & 3) or (2 & 3) RAM configuration require memory
with tighter specs than using (1 & 2)? I'll buy some Crucial DDR3200,
but only if I'm sure that is the fix. FWIW, I'd bet my board's been out
of warrantee for about 30 minutes...
All being said and done it's been a great board. I just want to know
why I can't do something the manual says I (or rather, the board), can
do.
thx,
r
I don't think the warranty will help in this case. I've got a
A7N8X-E Deluxe, so I've already been through this.
The problem is, the Nforce2 chip is not happy doing dual channel
at DDR400. You don't give enough details in your post, as to
the exact conditions you are applying to your system, but that
is where things seem to get harder. I was able to run dual
channel at 185MHz memory clock or so, but with my original RAM,
could not hit 200MHz.
Dual channel is demanding because there are 160 logic signals
all changing state at the same time. Chips must have lots of
VCC and GND pins on them, to handle the switching currents
involved. It would seem the Nforce2 was designed more for
DDR333 than for DDR400, if you read enough posts about
various brands of Nforce2 based boards. (I'd send you over
to nforcershq.com immediately, to read all about it, but
they've changed their search engine, and I doubt you'll
be able to find anything now via their search.)
You've already learned one of the workarounds. That is to
go single channel. With RAM in slot 1 and slot 2, only
80 logic signals are chugging away, which is why that will
work better. I think I managed to squeeze DDR400 out of that,
but perhaps it wasn't entirely error free.
Another workaround, is to get a hacked BIOS and load it in
place of a standard Asus BIOS. The parameter you are
interested in there, is called "Command Rate". Changing
command rate (a.k.a command per clock) from 1 clock cycle
to 2 clock cycles, gives an extra cycle of setup for
address/command signals to the RAM. But doing so, wastes
a bus cycle, and when benchmarking, you'll see about
as much performance degradation, as if you had just
turned the clock down in the first place. I.e. Running
CPC off at 230MHz clock is about the same as running
CPC on at 200MHz clock.
Use "CPC off" BIOS to run faster. I'm using the 1012
"CPC on" BIOS and never changed it back to an unhacked BIOS.
All Asus BIOS are "CPC on", which is command rate 1T.
http://forums.pcper.com/showthread.php?t=352326
The bottom line is, all the workarounds cost memory bandwidth.
For me, the solution was to buy some PC3200 CAS2 memory
(I used PC3200 Ballistix, but other CAS2 should work just
as well). I haven't bothered to push the bus at all with
that stuff, but the system is now rock solid at 200x11 and
DDR400 dual channel 2-2-2-6, and will pass Prime95 or any
other test I can cook up.
One poster did report that some Crucial CAS3 memory worked
for him, but I really cannot say what the success rate is,
for using PC3200 CAS3 memory in dual channel mode with this
chipset.
You can also try giving the memory more voltage, but I don't
think the performance curve is steep enough to fix the
problem entirely by just changing voltage.
Take a browse through these forums, and make up your own mind:
http://www.nforcershq.com/forum/viewforum.php?f=27
Some varied results here:
http://www.nforcershq.com/forum/viewtopic.php?t=58989
PC3200 CAS2 memory will cost somewhere between $60 to $120 a
stick for 512MB. I would read as many real reviews, such as
in the nforcershq forums as you can, to get a good idea of
what works. What you want are reviews by people who know the
importance of testing for stability with memtest86, Prime95,
SuperPI, 3DMark and so on. People who test by just booting
WinXP are, well, wishful thinkers. They are the very same
people who never lift the hood of their car, to see if it
has enough oil or not
Paul
