Dual Channel Memory is no faster than single channel

[sondreal]

• I had an Ultra 1024MB DDR 400mhz stick in my computer.
• I replaced it with 1 GB (2 * 512) DDR 400mhz Dual Channel kit.
• When I run all memory tests the results are no better with the dual channel kit.
• I used Memtest 86 and tested all the sticks of memory and no problems showed up.
• Why doens't the memory test show better results for Dual Channel?

Thanks,

[David (PassMark)]

It might be that you have the RAM in the wrong slots. Or it might be that your MB doesn't support dual channel.

It would have been good if you posted the before and after numbers.

[lee_sov]

I recently ran the test on a machine with 2gb ram ( 2 x 1gb sticks) using dual channel, I then removed 1 of the sticks and ran the test again (only single channel) and received a higher rating! Dont understand how that can be, surely double the ram would produce a higher score?

[sondreal]

I'm using the Abit Av8 board. It says that the ram needs to be in slot 1 and 2 or 3 and 4 for dual channel to work. I have the ram in slot 1 and 2 and havent noticed any performance increase running the memory test.

[sondreal]

I orginally said the results were no better with the dual channel. I should have said they are barely better.

Here are the numbers:

1GB single channel:
memory allocate small block - 1923.8
memory read cached - 1077.8
memory read uncached - 964.5
memory write - 862.7
memory large ram - 186.5
memory mark - 370.8
passmark rating - 66.7

1GB (2* 512MB) dual channel:
memory allocate small block - 1943.5
memory read cached - 1090.3
memory read uncached - 972.1
memory write - 946.1
memory large ram - 219.7
memory mark - 382.3
passmark rating - 68.8

[David (PassMark)]

The allocate & cached memory test shouldn't be greatly effected because they don't use the full bandwidth of main RAM much.

Yes, your 5% to 10% increase does look a little low. I am not sure as to the reason. I wouldn't assume anything is wrong unless you sure much larger increases from other motherboards. (I don't have any numbers handy to tell you what you should expect from this type of comparison)

[sondreal]

Thanks for your explanation.
I don't have another mobo to test this scenario on.
If i get another board that can run dual channel memory i will test the sticks and update this post with the results, although I don't think i will be getting another one anytime soon.

[Willyboy]

I run 2 x 512 gb mem in Dual Channel , In my ageing GA-7N400pro2 gigabyte mobo & they are bit tetchy ! when it comes down to how much memory it will take ..supposedly 3gb but to do that special single side DDr as to be used in the 2 remaining slots.. also 2x 1GB will not run correctly in dual channel im told by gigabyte @ 400Mhz cuts down to 333Mhz !!!
So i put 1 x 512 in the 3rd slot thus cancelling the Dual channel but had a total of 1.5 gb memory installed , didnt do much testing other than running 3Dmk 2006 .....Outcome was the score went down with the extra memory !! so dual channel does improve performance some what ..

[sondreal]

Dual channel faster with other memory benchmarking software

I decided to try another mobo in my machine because i thought my mobo wasn't recognizing the dual channel ram because of the results i saw with performanceTest. I again noticed a very small performance increase when comparing dual channel (2 by 512) compared to 1 GB stick.

I decided to try another memory benchmarking package. I ran the memory bandwidth test in Si Software Sandra and noticed the numbers in dual channel were almost double of that when running the 1 GB stick.

I decided to download additional memory benchmarking packages and saw the numbers were always much higher (almost double) when comparing the 1GB stick to the dual channel kit.

I'm not sure why performance test is not showing significant improvements when running in dual channel. If anyone has any ideas please let me know.