Dual Channel Mem on A7N8X-E..limited understanding

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alo

Hello...

I have A7N8X-E and I want to install a pair of PC3200 512MB Dual
Channel memory sticks on it. (Geil memory)

It was running OK on one strip of PC3200 memory in DIMM A1.

I took that out, and put the two new items in DIMM A1 and DIMM A2. The
computer booted up OK.

Reading the manual (if I understand it correctly) it suggests that
Dual-channel memory should go into A1 and B1 (leaving A2 empty)

I tried this and the motherboard reported that the CPU was overclocked
and the booting process stopped, I was unable to get into winXP.

I have now put them back into A1 and A2, and get winXP running again.

I am not too sure what or why this happened, am I going wrong
somewhere?

TIA

Regards
 
Hello...

I have A7N8X-E and I want to install a pair of PC3200 512MB Dual
Channel memory sticks on it. (Geil memory)

It was running OK on one strip of PC3200 memory in DIMM A1.

I took that out, and put the two new items in DIMM A1 and DIMM A2. The
computer booted up OK.

Reading the manual (if I understand it correctly) it suggests that
Dual-channel memory should go into A1 and B1 (leaving A2 empty)

I tried this and the motherboard reported that the CPU was overclocked
and the booting process stopped, I was unable to get into winXP.

I have now put them back into A1 and A2, and get winXP running again.

I am not too sure what or why this happened, am I going wrong
somewhere?
Click to expand...

Yep, to run dual-channel you need them in slots A1 and B1. However,
the nForce2 chipset is a bit picky about RAM when running in dual-
channel, so it simply might not 'like' your Geil sticks. If you're running
at 200MHz FSB, check that BIOS memory settings are at 200MHz
(100%) and not "by SPD" which might be a problem if your sticks
have incorrect SPD details programmed into them.
There are quite a few other BIOS settings you can try as well, like
raising the RAM voltage by a notch, relaxing the timings slightly
etc. A google for "a7n8X-e BIOS memory settings" should bring
up some useful stuff.
HTH
 
Hello...

I have A7N8X-E and I want to install a pair of PC3200 512MB Dual
Channel memory sticks on it. (Geil memory)

It was running OK on one strip of PC3200 memory in DIMM A1.

I took that out, and put the two new items in DIMM A1 and DIMM A2. The
computer booted up OK.

Reading the manual (if I understand it correctly) it suggests that
Dual-channel memory should go into A1 and B1 (leaving A2 empty)

I tried this and the motherboard reported that the CPU was overclocked
and the booting process stopped, I was unable to get into winXP.

I have now put them back into A1 and A2, and get winXP running again.

I am not too sure what or why this happened, am I going wrong
somewhere?

TIA

Regards
Click to expand...

This is the fault of Nvidia and not you as the user.

The Northbridge is not really designed well enough to work
with most commodity RAM. I fixed mine by using two sticks
of DDR400 CAS2 ram, as my CAS3 RAM gave the same symptoms
as you. It almost seems like the Northbridge doesn't have
enough power/ground pins on it, to feed it clean power.
(The technical terms are "simultaneous switching noise"
and "rail collapse".)

Things that work, sort of...

1) Operate in single channel mode. Use A1+A2.
This shuts down one channel on the Northbridge, making it
electrically quieter, as there is less switching noise.
2) Operate in dual channel mode (A1+B1), but drop the FSB
to 180-185MHz, instead of 200MHz.
3) Find a hacked BIOS that runs 2T command rate timing.
Unfortunately, this option is not provided in a standard
BIOS. I have used the "Trat" BIOS from nforcershq.com
for this purpose. You can run with a 200MHz clock in
dual channel this way, but the memory bandwidth will
be reduced.

I don't remember if I tried 200MHz clock and selected
a lower ratio in the RAM settings. Possibly setting the
RAM to 83% would work. That would be like (2), but in
(2) FSB=185 and MEM=185, while using a ratio, you
could try FSB=200 and MEM=166 and see if it works any
better.

The final solution for me, was to buy some PC3200 CAS2
memory.

You can tell when you've got marginal operation, as
you'll get the "failed due to overclock" at POST if
things are still not healthy (but the computer still
boots). That is telling you the RAM is not quite right.
When the ram is right, there are no vocal post messages.

An even better test, is to run Prime95 torture test
(mersenne.org), as it will error out in 30 minutes or
less when your RAM isn't fixed. With my CAS2 ram now,
I'm Prime95 "clean".

There are some people who get CAS3 RAM to work, but I
cannot tell you how common an experience that is.

Good luck,
Paul
 
This is the fault of Nvidia and not you as the user.

The Northbridge is not really designed well enough to work
with most commodity RAM. I fixed mine by using two sticks
of DDR400 CAS2 ram, as my CAS3 RAM gave the same symptoms
as you. It almost seems like the Northbridge doesn't have
enough power/ground pins on it, to feed it clean power.
(The technical terms are "simultaneous switching noise"
and "rail collapse".)
Click to expand...

Paul...

Thanks for the information, I have spent some time since my original
post going back over similar problems with this board in this
newsgroup.

There has been plenty of postings on the subject. My head got a bit
dizzy after an hour or two! :-)

I tried a few alterations with the memory and clock speed... but
things only got worse.

Thank goodness I had a Ghost image of the drive before I started
altering things around... I set the BIOS back to its original
settings, and reloaded from Ghost 2003.

I think I will settle for running these two strips in slot 1 and 2,
life is too short to spend anymore time or money to crack this
problem, if my system is stable then I will be happy.

Regards
 
alo said:
Paul...

Thanks for the information, I have spent some time since my original
post going back over similar problems with this board in this
newsgroup.

There has been plenty of postings on the subject. My head got a bit
dizzy after an hour or two! :-)

I tried a few alterations with the memory and clock speed... but
things only got worse.

Thank goodness I had a Ghost image of the drive before I started
altering things around... I set the BIOS back to its original
settings, and reloaded from Ghost 2003.

I think I will settle for running these two strips in slot 1 and 2,
life is too short to spend anymore time or money to crack this
problem, if my system is stable then I will be happy.

Regards
Click to expand...

AMD systems tend to be more "hands on", and require more
attention to details. There are an infinite number of
workarounds out there, and certainly the hacked BIOS that
have command rate set to 2T, are the best for being able to
run the FSB at its rated speed.

You may get your A1+A2 combo to work, but test it thoroughly
before concluding the system is ready for use with real
disks and data.

I tested my system using a Knoppix boot CD. By doing that,
no data on a hard drive is endangered, as Knoppix uses a RAM
disk to hold the working data. With Knoppix CD, you can watch
the boot sequence, and have a pretty good idea of how screwed
up your system is. For example, I had several windows open
in the Linux desktop, and one by one they disappeared, as
the programs driving the window crashed. It is an entertaining
and harmless way of verifying how well the processor and
memory are doing. When memtest86+ and Prime95 can run
cleanly, then it is safe to reconnnect the hard drive.

Paul
 
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