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1GB Dual Channel vs. 2GB Single Channel? Which is better?

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May 26, 2007 6:05:19 PM

Hi all, my wife is about to upgrade to 2GB on her 2 slot board, which means I will inherit her 2 512MB sticks for my 4 slot board. I am currently running 2x512 PQI DDR 400 in Dual Channel mode. Her memory is PQI as well, however one of the sticks isn't matched and the system will only run the four sticks together in single channel mode. Am I going to take a performance hit here? Should I just stick with what I've got with the 1GB single channel?

Thanks in advance!
May 26, 2007 6:32:49 PM

Assuming you are running Windows, you're almost always better off having more RAM, even at the cost of reduced RAM speed, as the RAM is still much faster than swapping to the hard disk.
May 26, 2007 6:33:05 PM

Dual channel mode is much faster. Upgrade her machine to 2x1GB to maintain dual-channel mode.

Ryan
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May 26, 2007 7:02:35 PM

Quote:
Dual channel mode is much faster. Upgrade her machine to 2x1GB to maintain dual-channel mode.

Ryan


Please....

Given the age of the machines he is talking about, its likely 2 Athlon XP systems.

In which case, as the FSB bandwidth is saturated with single channel DDR, there is no more than a 2-3% benefit from dual channel.

Dual channel mode is not "much faster".

Under some circumstances it can make some difference, but not many. Hell when I had 3 1GB DIMMs, I noticed a less than 2% difference in 3Dmark06 scores between 2GB dual channel and 3GB single channel, and thats on a C2D which is not FSB limited.

2GB single channel is vastly superior to 1GB dual channel.
May 26, 2007 8:00:55 PM

Thanks, to clarify, we're talking about 2 Athlon 64 systems. One 754 socket, and one 939, but neither can use DDR2.
May 26, 2007 9:52:20 PM

Quote:
Dual channel mode is much faster. Upgrade her machine to 2x1GB to maintain dual-channel mode.

Ryan


Please....

Given the age of the machines he is talking about, its likely 2 Athlon XP systems.

In which case, as the FSB bandwidth is saturated with single channel DDR, there is no more than a 2-3% benefit from dual channel.

Dual channel mode is not "much faster".

Under some circumstances it can make some difference, but not many. Hell when I had 3 1GB DIMMs, I noticed a less than 2% difference in 3Dmark06 scores between 2GB dual channel and 3GB single channel, and thats on a C2D which is not FSB limited.

2GB single channel is vastly superior to 1GB dual channel.

I guess you can insert your foot in your mouth now. You what they say when you assume?
May 26, 2007 10:00:27 PM

Quote:
Thanks, to clarify, we're talking about 2 Athlon 64 systems. One 754 socket, and one 939, but neither can use DDR2.


I doubt you run 3DMark on a day to day basis so darkstar782's point doesn't matter much. I had an old P4 system that was much different in dual and single channel mode. Your A64s are faster and thus benefit from more bandwidth as well.

I should have elaborated earlier. How come it won't run in dual channel mode if you have 4 512MB DDR400 sticks? RAM is so cheap now, replace 1 with something that will match and you will reap the benefits of more RAM and dual channel mode. The 2GB you will end up with will only help you if your day to day use requires more than 1GB. An easy way to get an idea of how much will benfit you, after using your machine for a while with the apps you typically run, open Task Manager. On the performance tab, look at "Peak" under "Commit Charge." If it is more than 1GB, more RAM will speed up the system. Hopefully that is more helpful.

Ryan
May 26, 2007 11:08:05 PM

Well you assumed they didn't have an Athlon XP based system with your blanket "its much faster" statement. At least I pointed out that there was some basis for it and it didn't cover everything.

I doubt he DOES run 3Dmark06 all day, but he probably plays games, and it is doubtful he runs Everest/Sisoft Sandra/WinRAR's Benchmark all day either, which are about the only things that will show a noticeable benefit from Dual channel operation.

You are honestly telling me that you believe games would run better with 1GB Dual Channel than 2GB Single channel?



My Core 2 Duo e6700 is faster than either your old P4 or his A64, so according to your statement:

Quote:
I had an old P4 system that was much different in dual and single channel mode. Your A64s are faster and thus benefit from more bandwidth as well.


I should benefit even more yes?

Strange then how I found that 3*1GB Dual Channel Async (where the memory addresses are not at all interleaved, there is just one point where it switches from one channel to the other where there is a possible speed gain) was faster than 2*1GB Dual Channel Interleaved with multiple applications, and only 2-3% slower in 3Dmark06, and FASTER in games like BF2142, because in the real world I keep my IM clients and Bittorrent software and web browser open when playing.


Shall we bring some real benchmarks into this? Lets!

Clicky

Note for people that don't know any better: S754 CPUs have a single channel memory controller therefore the S754 CPU here has its RAM running in single channel. S939 is running in dual channel, S940 is dual channel with registered DIMMs.

All the CPUs are @ the same speed with the same cache.

I feel these benchmarks are pretty appropriate due to being early A64 benches, which are what the OP is running.

According to you there should be massive differences between single and dual channel operation. Guess what, the differences are negligible at best!

If you click the next page you'll see gaming performance, again negligible difference!

So, we have established that Dual channel gives some negligible performance gains. However, for most applications 2GB RAM gives a far LARGER performance gain, especially for modern games.

Hence, I stand by my original post.

Oh, and please get a clue, and at least know what you are talking about before you start being offensive next time.
May 27, 2007 1:10:24 AM

Since the OP didn't specify what hardware he was running, it was safe for me to assume they were Netburst based systems since more than 80% of computers in use are Intel based. Have you ever used a P4 in single channel vs dual channel mode? (shudders) Even in the link you provided, Anand explains how Intel benefits tremendously from dual channel mode.

What if the OP never goes beyond 1GB of RAM? You never asked what he does with the machine. You just assumed he plays games. You even said given the age of the machines, they are likely Athlon XP machines. Where the f*** did you get that? He made no such mention of the age either.

In your last post you still assumed they were early systems. Maybe he built the 939 system a year ago.

At least I based my assumption on statistical probability. Alas, we were both wrong. The reality is, I just don't care about this enough to continue. I made a weak attempt at humor and apparently offended you. For this I am sorry. These forums have unfortunately become so hostile over the past several months. What happened to trying to help people with similar interests and discussing new tech with other enthusiasts without all this bickering.

Ryan
May 27, 2007 2:27:51 AM

Quote:
Since the OP didn't specify what hardware he was running, it was safe for me to assume they were Netburst based systems since more than 80% of computers in use are Intel based.


A second ago you were telling me how wrong I was for making assumptions :p 

Quote:
Have you ever used a P4 in single channel vs dual channel mode? (shudders)

Yes thanks, had a Pentium D 805 for a while.


Quote:
Even in the link you provided, Anand explains how Intel benefits tremendously from dual channel mode.

Cant see it anywhere that he says the gain is "tremendous".


Quote:
What if the OP never goes beyond 1GB of RAM? You never asked what he does with the machine. You just assumed he plays games. You even said given the age of the machines, they are likely Athlon XP machines. Where the f*** did you get that? He made no such mention of the age either.


He also said that his wifes machine was being upgraded to 2GB and that his question was about the fact that he couldn't get 4 DIMMs to run in Dual Channel on his system. Seems you cant read as you started going on about what he should upgrade his wife's machine to to maintain dual channel operation.

I was mainly pointing out that your "dual channel is much faster" statement DEFINITELY isn't as universal as you made out. Athlon XPs have almost no benefit from it.

As for games? Most home users that post here play games, but even for general Windows use he is imho better with 2GB than 1GB being as he has the DIMMs there. Even if the system never goes over 1GB, Windows' memory management is not the best and it will start swapping to disk a long time before it runs out of RAM.

Still, if he is caring about the performance he must be doing SOMETHING demanding with his PC, and most things would benefit from 2GB these days more than they would from 1GB dual channel, whether it be Games, Photoshop, Rendering, whatever.

Quote:
In your last post you still assumed they were early systems. Maybe he built the 939 system a year ago.

Makes no difference if it was, Athlon 939 didn't suddenly start to benefit from dual channel later in its life.

Quote:
At least I based my assumption on statistical probability.

But you didn't mention you had made an assumption, you just made a blanket statement.


ANYWAY.....

Pentium 4 benefits tremendously from dual channel does it? hehe....

Click Me

5 Intel boards. The 865 and 875 are Dual Channel DDR1 boards. The 848 has a single channel memory controller. As the 900 series intel chipsets mark the DDR2/PCIe era, and anything earlier is RDRAM, I assume these were the boards that showed your "tremendous" difference.

Oh look! the single channel board finishes middle of the pack for most of the tests, and the ones it is behind in it isn't by much!

So much for your "tremendous" difference.

I'll grant you the single channel board DOES loose out quite a bit on rendering tasks, but these are pretty RAM hungry and would more than likely benefit more from 2GB than they loose from single channel mode.
!