AMD64 in Dual Channel

[Lee Waun]

After years of being a loyal Intel user I have finally left them. Having
read this group and comp.sys.intel for years now it was pretty clear that
Intel has fallen far behind AMD in quality and performance in thier
processors.

Anyway I just replaced my aging Pentium 4 with a brand new AMD64 Athlon. I
wanted a machine that was upgradeable and had the future of 64 bits built in
it and so I chose the AMD 64 3500+ CPU for the 939 socket.

It is on a Nforce4 chipset motherboard. It says it has Dual channel memory.
However when I got the system home it was running in single channel. The
machine has 1 gig of memory which I should hope is enough for now. I changed
the memory to dual channel but I am just wondering.

Just how much performance if any would I have lost by keeping the machine is
single channel mode or would I be better off having it in single channel
mode istead of switching it to Dual channel mode?

So far this AMD machine is real nice and I am very happy with it. It runs as
cool as my old Northwood Pentium 4 did.

 

[Yousuf Khan]

Just how much performance if any would I have lost by keeping the machine is
single channel mode or would I be better off having it in single channel
mode istead of switching it to Dual channel mode?

I doubt you'd be able to feel the difference between single and dual
channel modes on a personal basis. The only things that could tell would
be benchmarks.

Yousuf Khan

 

[Nate Edel]

I doubt you'd be able to feel the difference between single and dual
channel modes on a personal basis. The only things that could tell would
be benchmarks.

Or if he runs long-running compute-intensive jobs.

The one thing some people I know do that would come under "general hobbyist
use" that might noticeably be affected is video encoding (home video to
mpeg2/4, dvds to mpeg4, or mpeg2 transcoding to copy DVD9 disks to
DVD-/+R...) ... though it's probably still in the range of a few minutes on
multiple-hour jobs.

 

[dawg]

After years of being a loyal Intel user I have finally left them. Having
read this group and comp.sys.intel for years now it was pretty clear that
Intel has fallen far behind AMD in quality and performance in thier
processors.

Anyway I just replaced my aging Pentium 4 with a brand new AMD64 Athlon. I
wanted a machine that was upgradeable and had the future of 64 bits built in
it and so I chose the AMD 64 3500+ CPU for the 939 socket.

It is on a Nforce4 chipset motherboard. It says it has Dual channel memory.
However when I got the system home it was running in single channel. The
machine has 1 gig of memory which I should hope is enough for now. I changed
the memory to dual channel but I am just wondering.

Just how much performance if any would I have lost by keeping the machine is
single channel mode or would I be better off having it in single channel
mode istead of switching it to Dual channel mode?

So far this AMD machine is real nice and I am very happy with it. It runs as
cool as my old Northwood Pentium 4 did.

There is no difference between so called dual channel memory and normal DDR
ram. Dual channel is enabled by using two similar DDR ram modules. They
usually need to match speed,capacity and manufacturer,but that's it.
So,what did you do to enable dual channel? Did the PC have just one 1GB
module?

 

[George Macdonald]

After years of being a loyal Intel user I have finally left them. Having
read this group and comp.sys.intel for years now it was pretty clear that
Intel has fallen far behind AMD in quality and performance in thier
processors.

Anyway I just replaced my aging Pentium 4 with a brand new AMD64 Athlon. I
wanted a machine that was upgradeable and had the future of 64 bits built in
it and so I chose the AMD 64 3500+ CPU for the 939 socket.

It is on a Nforce4 chipset motherboard. It says it has Dual channel memory.
However when I got the system home it was running in single channel. The
machine has 1 gig of memory which I should hope is enough for now. I changed
the memory to dual channel but I am just wondering.

Just how much performance if any would I have lost by keeping the machine is
single channel mode or would I be better off having it in single channel
mode istead of switching it to Dual channel mode?

The performance difference is maybe hard to see in most applications but if
you run some tests with a benchmark prog like Sisoft's Sandra, it'll be
obvious in measured bandwidth. There's no advantage to single channel so
why not just leave it in dual.

So far this AMD machine is real nice and I am very happy with it. It runs as
cool as my old Northwood Pentium 4 did.

Have you checked that Cool 'n' Quiet is working? It should idle at ~1GHz
clock speed and ramp up quickly as required. I'd make sure you have the
latest AMD driver from
http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_871_9706,00.html
installed, which is quite recent, make sure Cool 'n' Quiet is enabled in
BIOS Setup and in WinXP's Power Options Control Panel, set it to "Minimal
Power Management".

 

[Lee Waun]

Or if he runs long-running compute-intensive jobs.

The one thing some people I know do that would come under "general
hobbyist
use" that might noticeably be affected is video encoding (home video to
mpeg2/4, dvds to mpeg4, or mpeg2 transcoding to copy DVD9 disks to
DVD-/+R...) ... though it's probably still in the range of a few minutes
on
multiple-hour jobs.

Well the change over to dual channel has made this machine so snappy and
quick today that I went out and bought a second gig of DDR 400 Ram so now I
am running this AMD 3500+ with 2 gigs in dual channel mode and the machine
is just a killer. Nothing but floppy disks slow this machine down now. I am
using windows XP but will be switching to windows 64 as soon as there are
drivers for my hardware. My printer is not expecting to get any 64 bit
drivers for a few months so I will just stay with 32 bit windows until there
are decent drivers for my hardware.

 

[Lee Waun]

There is no difference between so called dual channel memory and normal
DDR
ram. Dual channel is enabled by using two similar DDR ram modules. They
usually need to match speed,capacity and manufacturer,but that's it.
So,what did you do to enable dual channel? Did the PC have just one 1GB
module?

No I had 2 512meg modules but to be in dual mode they have to be in the two
slots beside each other. (slot one and two.) One stick of memory was in slot
3 so the machine and cpu Z reported the memory was in single channel mode.
Put the second stick in slot 2 and it changed to dual channel and tonight I
bought 2 more sticks of 512 meg DDR400 memory and now have 2 gigs running in
dual channel mode. Now am just waiting for 64 bit drivers so I can upgrade
the operating system.

 

[Lee Waun]

The performance difference is maybe hard to see in most applications but
if
you run some tests with a benchmark prog like Sisoft's Sandra, it'll be
obvious in measured bandwidth. There's no advantage to single channel so
why not just leave it in dual.

Yes I am leaving it in dual mode as I paid extra money for dual channel
motherboard and I want what I paid for. Also I upgraded the memory to an
extra gig so now the machine is in dual mode at 2 gigs. It is real nice. I
have no software now that will slow this machine down. It is so nice.

Have you checked that Cool 'n' Quiet is working? It should idle at ~1GHz
clock speed and ramp up quickly as required. I'd make sure you have the
latest AMD driver from
http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_871_9706,00.html
installed, which is quite recent, make sure Cool 'n' Quiet is enabled in
BIOS Setup and in WinXP's Power Options Control Panel, set it to "Minimal
Power Management".

Yup that part is already done.

 

[YKhan]

Yes I am leaving it in dual mode as I paid extra money for dual channel
motherboard and I want what I paid for. Also I upgraded the memory to an
extra gig so now the machine is in dual mode at 2 gigs. It is real nice. I
have no software now that will slow this machine down. It is so nice.

Well maybe your next memory test, apart from single- vs. dual-channel,
should be to see if you can't overclock the RAM somewhat. I'd
particularly try overclocking the latency settings rather than
overclocking the clock. Lowering the latency can only help to make it
feel even snappier.

Yousuf Khan

 

[George Macdonald]

Well maybe your next memory test, apart from single- vs. dual-channel,
should be to see if you can't overclock the RAM somewhat. I'd
particularly try overclocking the latency settings rather than
overclocking the clock. Lowering the latency can only help to make it
feel even snappier.

I've found that the 1T command rate setting is by far the most important
setting for an Athlon64 - even if you have to back off the CAS latency to 3
to achieve it, it's worth nearly 1GB/s in a bandwidth test vs. 2T. I
believe the latest Ex chips have improved capability here but you need to
keep the rank count down for best results... and the Crucial 512MB DIMMs
with 8 chips have worked well for me in this respect. They were even on
sale at NewEgg recently.

 

[Lee Waun]

Well maybe your next memory test, apart from single- vs. dual-channel,
should be to see if you can't overclock the RAM somewhat. I'd
particularly try overclocking the latency settings rather than
overclocking the clock. Lowering the latency can only help to make it
feel even snappier.

Yousuf Khan

At this point I can't see how it could get much snappier but I will check
this out.

 

[YKhan]

Here's an article comparing various RAMs tweaked up against each other.

Welcome to AnandTech.com [ Article: Athlon 64 Memory: Rewriting the
Rules]
http://www.anandtech.com/printarticle.aspx?i=2226

There was another one which was even better I thought, but I can't seem
to find it anymore.

Yousuf Khan