New system...won't run dual channel memory??

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Neck & Red

Hey guys, looking for some insight here..I've built a new system around an
Athlon 64 Dual Core 3800+, Abit KN9 motherboard, and a pair of 1 gig sticks
of G.Skill PC800 memory.

Problem is, the system won't run stable when the memory sticks are running
dual channel. For example:

With a stick in DIMM1 and DIMM2, system gets a BSOD, random reboots, and
sometimes won't boot at all. POST screen says 2 gigs of memory at 128 bit
dual channel.

Remove the stick from DIMM1 (running just DIMM2) I can't make the system
lock up. It runs beautifully. On the post screen it now says 1 gig of memory
running at 64 bit single channel.

With 2 sticks in DIMM3 and DIMM4 it seems to run better than DIMM1 and
DIMM2, but eventually will lock up or reboot. POST says 2 gigs 128 bit dual
channel.

Remove either one, runs fine...POSTS at 1 gig 64 bit single channel.

Now I have a stick in DIMM 2 and a stick in DIMM4. It says 2 gigs, 64 bit
single channel.

So, basically any configuration that yeilds 128 bit dual channel memory
won't run, and any combo that yeilds 64 bit single channel runs great.

Any ideas why?? This seems nutty :)

Looking for advice before I replace the G. Skill with OCZ or something, just
don't want to spend any more money at this point if it won't help.
 
Hey guys, looking for some insight here..I've built a new system around an
Athlon 64 Dual Core 3800+, Abit KN9 motherboard, and a pair of 1 gig sticks
of G.Skill PC800 memory.

Problem is, the system won't run stable when the memory sticks are running
dual channel. For example:

With a stick in DIMM1 and DIMM2, system gets a BSOD, random reboots, and
sometimes won't boot at all. POST screen says 2 gigs of memory at 128 bit
dual channel.

Remove the stick from DIMM1 (running just DIMM2) I can't make the system
lock up. It runs beautifully. On the post screen it now says 1 gig of memory
running at 64 bit single channel.

With 2 sticks in DIMM3 and DIMM4 it seems to run better than DIMM1 and
DIMM2, but eventually will lock up or reboot. POST says 2 gigs 128 bit dual
channel.

Remove either one, runs fine...POSTS at 1 gig 64 bit single channel.

Now I have a stick in DIMM 2 and a stick in DIMM4. It says 2 gigs, 64 bit
single channel.

So, basically any configuration that yeilds 128 bit dual channel memory
won't run, and any combo that yeilds 64 bit single channel runs great.

Any ideas why?? This seems nutty :)

Looking for advice before I replace the G. Skill with OCZ or something, just
don't want to spend any more money at this point if it won't help.
Click to expand...

The first thing I'd do is check to see if the BIOS is at the latest rev,
if it isn't then I'd update it (use only one stick of memory when you are
doing the BIOS update, you don't want the system to crash when you are
doing it).

If the BIOS is OK I'd try reducing the clock on the DIMMs from 800MHz to
667MHz, it won't make much difference in your system performance and it
should fix your timing problems.
 
The first thing I'd do is check to see if the BIOS is at the latest rev,
if it isn't then I'd update it (use only one stick of memory when you are
doing the BIOS update, you don't want the system to crash when you are
doing it).

If the BIOS is OK I'd try reducing the clock on the DIMMs from 800MHz to
667MHz, it won't make much difference in your system performance and it
should fix your timing problems.
Click to expand...

This is me just with a new logon...I'm on my new machine now.

Thanks for the ideas, but let me ask you this...

...what would give better performance, lowering the timing to 667 and running
them dual channel, or keeping them 800mhz and staying single channel?
 
This is me just with a new logon...I'm on my new machine now.

Thanks for the ideas, but let me ask you this...

..what would give better performance, lowering the timing to 667 and running
them dual channel, or keeping them 800mhz and staying single channel?
Click to expand...

Dual channel 667 would be much better than signal channel 800MHz. Dual
channel 667 is 10.672GBytes/sec, single channel 800 is 6.4GBytes/sec.
 
Dual channel 667 would be much better than signal channel 800MHz. Dual
channel 667 is 10.672GBytes/sec, single channel 800 is 6.4GBytes/sec.
Click to expand...

One more thing, I bet when you put both DIMMs on the same channel the BIOS
is setting the speed to 667. Chances are that the DIMMs are double sided,
two double sided DIMMs is a fairly large load, it would make sense for the
BIOS to automatically scale the clock back if it detects two double sided
DIMMS. When you boot the system the BIOS will tell you what speed the RAM
is running at.

There is something else you can do besides reducing the clock rate, you
could increase the voltage to the RAMs slightly. The BIOS will tell you
what the safe values are. Also if you haven't already done it you should
download Memtest86+ and run that. I also provide a system exerciser which
is much more severe then Memtest86+,

http://www.polybus.com/sys_basher_web/

Sys_basher is for Linux but it's open source and you are free to port to
Windows if you want. The only thing that would have to change is the
thread library calls. Sys_basher uses pthreads. I'm pretty sure that
pthreads is available for Windows but it's not standard. There is a
Windows equivalent which does the same thing. I only use a couple of calls
so it would be fairly easy for someone who know something about Windows
programming to change it.
 
One more thing, I bet when you put both DIMMs on the same channel the BIOS
is setting the speed to 667. Chances are that the DIMMs are double sided,
two double sided DIMMs is a fairly large load, it would make sense for the
BIOS to automatically scale the clock back if it detects two double sided
DIMMS. When you boot the system the BIOS will tell you what speed the RAM
is running at.
Click to expand...

I sure do appreciate all the info, I'm going to fool around with it when I
get some time. RAM is one area that I'm not familiar with tweaking. Usually
I just stick it in and it works, I've never played around with timing and
voltages.

But until then, let me ask you this...could this be a case of some funky
RAM? I've never used G. Skill before, but it was about $75 less than the
HyperX or Crucial that I normally use and maybe that says something right
there. I'm temped to order some more RAM just to see, but that's an
expensive test.
 
I sure do appreciate all the info, I'm going to fool around with it when I
get some time. RAM is one area that I'm not familiar with tweaking. Usually
I just stick it in and it works, I've never played around with timing and
voltages.

But until then, let me ask you this...could this be a case of some funky
RAM? I've never used G. Skill before, but it was about $75 less than the
HyperX or Crucial that I normally use and maybe that says something right
there. I'm temped to order some more RAM just to see, but that's an
expensive test.
Click to expand...

I'm using GSkill 2G DIMMs and they are working fine. Admittedly from a
statistical standpoint that's a meaningless statement but I don't think
there is anything wrong with the brand.

One thing that seems to have happened with DIMMs is that there doesn't
seem to be a voltage standard anymore, every model of DIMM seems to have a
different voltage. Setting the voltage wrong seems to be a commonly
reported problem which is why I suggested that you update your BIOS to the
latest rev. Raising the voltage will generally improve the signal levels,
but it will also make your DIMMs run hotter. Lowering the clock rate is
the best way to improve reliability, it will improve the timing margins
and reduce the temperature of the DIMMs. If you have a performance
critical application you can benchmark it at different RAM speeds, my
guess is that you'll only see a 1 or 2% difference in performance for
DDR667 vs DDR800.
 
One thing that seems to have happened with DIMMs is that there doesn't
seem to be a voltage standard anymore, every model of DIMM seems to have a
different voltage.
Click to expand...

Well it seems you're right about that! I upped the voltage from 1.8v to 2.0v
and she's rocking at dual channel 800mhz now! Thanks for all your help, I
really appreciate it. I've been running about 3 hours now full steam,
burning DVD's while playing HD videos and ripping MP3's and nary a hiccup :)
 
Hole In The Earth said:
Well it seems you're right about that! I upped the voltage from 1.8v to
2.0v and she's rocking at dual channel 800mhz now! Thanks for all your
help, I really appreciate it. I've been running about 3 hours now full
steam, burning DVD's while playing HD videos and ripping MP3's and nary a
hiccup :)
Click to expand...
HITE, you hit the nail on the head, so to speak re memory voltage. I'm
looking at
G.Skill PC800 on Newegg, and minimum voltages vary from 1.8 to 1.9 to 2.0.
So, depending on which sticks you got the bump to 2.0v got you where you
needed
to be.

Jeff
 
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