Quick question about Dual Channel RAM

[dme92189]

Hey there guys,
So here is the question. If I have 2 sticks of 512MB DDR400 RAM running in dual channel now, and have a spare stick of 256MB DDR400 lying around, should I forgo the Dual channel and take the 1.3 GB of ram or use the Dual Channel and take 1 GB of RAM?

Thanks!
Dan

 

[dBTelos]

Stay dual channel. 256MB isn't a very big difference, and you would see the slower speeds.

 

[dme92189]

Really? Thats cool, anyone else think the same?

 

[pkme2]

Stay with the 2 sticks for 1GB.

 

[dguy6789]

We need to know what kind of system you are running on.

If Athlon 64: Take the 1.3GB. There is ZERO difference between dual channel and single channel on an Athlon 64 in the first place(due to it being so efficient with the on die memory controller), but with 1.3GB vs 1GB, it will be the harddrive thrashing and swapping once you have reached 1GB of used memory or perfect performance at 1GB used.

If Pentium 4: Keep the dual channel. Dual channel memory on a Pentium 4 platform can affect overall system performance by more than 10% in some scenarios.

 

[dme92189]

Yea I am using a A64, I ahve been doing some testing of my own, it seems like Dual channel may be faster by a small margin.

 

[dme92189]

Ok, so using PiFast, I calculated 50000000 iterations of Pi:
Single channel 1.3GB: 287.78 Seconds
Dual Channel 1 GB 259.84 seconds.
While this may not show much for storage, it shows a lot for the speed of Dual channel.
Any thoughts?

 

[dguy6789]

Super Pi has been shown to not be much of a real world test. If Super Pi was an accurate benchmark of system performance, then everyone here would be using Pentium M systems, as the Pentium M does the best in Super Pi, but in the real world tasks, it simply cannot hold a candle.

Run something more real world. Record the difference in fps of a game going from single channel to dual channel. Try burning a disc. Try doing anything. I guarentee that if someone went into your system and disabled dual channel without changing memory amount without you knowing, you would not notice any difference. Also, try running tests on the different memory sizes. Try running something that takes a gig of memory with 1GB, and then try running the same thing with 1.3GB of memory. I guarentee the difference in performance between 1.3 and 1GB when you are memory limited will be much larger than any difference between dual channel and single channel.

 

[bob4432]

Originally posted by: dguy6789
We need to know what kind of system you are running on.

If Athlon 64: Take the 1.3GB. There is ZERO difference between dual channel and single channel on an Athlon 64 in the first place(due to it being so efficient with the on die memory controller), but with 1.3GB vs 1GB, it will be the harddrive thrashing and swapping once you have reached 1GB of used memory or perfect performance at 1GB used.

If Pentium 4: Keep the dual channel. Dual channel memory on a Pentium 4 platform can affect overall system performance by more than 10% in some scenarios.

QFT

 

[dme92189]

Alright I will give that a go.

 

[allanon1965]

I would not go for a mere 256mb more ram with the 64...I run a 3000+ 64 and you can notice a difference between single channel(64Bit) and dual channel(128Bit), of course dependant on what you are using at the time. 256mb is not worth losing dual channel over....you will not see any benefit from the addtional ram...now if you were doing that with 512 or 1GB that would be a different story......I personally am running 2X1GB Dual channel and i notice a big difference plus if you add that 256, you may also lose optimum timings if the 256 doesnt support as good of timings as the rest of the ram...

 

[Bobthelost]

It's not going to make any positive difference if you never use more than 1GB, and while dual channel may not be as important to the A64 as the P4 it isn't going to do it any favours running it slower. (Not nessisarily slow it down, but certainly not speed it up).

As such if you're not using more than 1GB then don't bother, sell the RAM or donate it to a charity. If you are then those benchmarks would be nice to see (there are some around here already, but i forget where )

 

[bob4432]

Originally posted by: dme92189
Alright I will give that a go.

again, as other stated only add the additonal 256 if you are exceeding your 1GB already.

 

[dme92189]

Ok thanks guys! Turns out I just recieved two more 512Mbs that I ordered today, so I am now good! Thanks a ton for your help! Anandtech has a wonderful community!

Thanks!
Dan