Explain Dual Channel

[bikdel]

Having 2x1 gb DDR2 667 in Dual channel mode will theoretically make it work at par with... lets say 667x2= 1333 Mhz isnt it??...

I mean bnandwith doubles, so performance In terms of the RAM only should double... isnt it??

I wanted to know that if 2x1 GB ddr2 667 that i have in dual channel is gonna be a serious bottleneck for a QUAD CORE @ 1333 Mhz......

Please help me clarify this thing...

[shashank4u]

Dual channel mode not doubles the performance but its better than single channel mode....

If you serious about the bottleneck than go for kingston DDR3 1800MHz(high priced)

[bikdel]

that is grossly high priced and for the time beinfg, overpriced..........

man i wont be able to shell out 12 k for the ram only........

and i read in wikipedia is that the bandwith exactly doubles when dual channel mode is enabled
..........

[shashank4u]

you can always try DDR2 800/1033 MHz in dual channel mode and play safe

[BULLZI]

about dual channel:-

Consider the processor as an engine.An engine needs fuel to work.The fuel for processor is the data.

In dual channel architecture,the data from both of the rams goes simultaneously to the processor and the processor can get data faster and work faster too .The two rams are just like two funnels connected to the processor and through both these funnels,data are being sent to the processor.

2*1 GB ram wont bottleneck quad core.And after all,u can oc ur ram frequency to 750 mhz without any probs.

bt if u wanna be in safe side, get Corsair or OCZ PC2-6400 ram modules which are easily overclockable and great performers.

Just dont go for DDR3 ram rite now.They are ridiculously overpriced.

[The_Devil_Himself]

Originally Posted by BULLZI

Consider the processor as an engine.An engine needs fuel to work.The fuel for processor is the data.

In dual channel architecture,the data from both of the rams goes simultaneously to the processor and the processor can get data faster and work faster too .The two rams are just like two funnels connected to the processor and through both these funnels,data are being sent to the processor.

very well explained but you forgot to add one thing i.e.e if the two funnels used are of different sizes than both of them will work according to the size of the smaller one.

[naveen_reloaded]

Wow wow...is it true?
I have a 1gb ram in one plot and 512 in another .what will be the effect.sorry i dont know the frequency.
Just Ddr not II

[The_Devil_Himself]

^^no effect you need to have the same amount of RAM with same frequency in both the channels.
And most importantly your motherboard should support dual channel RAM.I don't think many mobos which has only ddr slots support this.

[bikdel]

I actually wanted to ask this thing...

FSB of My CPU = 1333 Mhz

Speed of My RAM = 667 Mhz = 1333/2 Mhz

So enabling Dual channel should double the bandwith and remove the bottleneck the RAM is putting on the processor's FSB , isnt it?

Pls clarify...

[The_Devil_Himself]

acutually dual channel doesnot mean 2x.Read and reread post no.5 and 6.
You can say dual channel is like RAID0 there is definitely some performance gains but not 2x.

[infra_red_dude]

Originally Posted by bikdel

I actually wanted to ask this thing...

FSB of My CPU = 1333 Mhz

Speed of My RAM = 667 Mhz = 1333/2 Mhz

So enabling Dual channel should double the bandwith and remove the bottleneck the RAM is putting on the processor's FSB , isnt it?

Pls clarify...

No no, you are mistaken. Consider this: Lets say we haf 10 people to be transported from station A to station B. There is only one lane and only one cab plies on it wid a max capacity of 5 people. The speed of the cab is fixed. Let say the cab takes 1 minute to transport 5 passengers from A to B. So this means to transport 10 people the cab will hafta make 2 trips and the total time will be 2 mins. This is single channel mode.

When the ram works in dual channel mode, something like this happens. Another lane gets added to the road and another cab of the same capacity and speed plies on the road. So both the cabs now work simultaneously and can transport 5 people each in 1 minute. So though 10 people are transported from A to B the time taken is only 1 minute (as both cabs haf the same speed). This is dual channel mode.

So think of dual channel mode as a wide road rather than a faster cab! Hence, tho the bandwidth (two lanes are added and hence the road becomes wider) increases, the speed of the cab (speed of the RAM = 667mhz in your case) remains the same, it doesn't double; though more data (from 5 to 10 people) is transfered. Hope that clears things.

[bikdel]

yeah dude i understand.......

but lets say performance wise dual channel should be better than single channel @ double speed....... lets say 667 mhz in dual channel should be better than single channel 1333 mhz...

why i am saying this is because
lets take the following example......

Pentium Dual Core E2140 @ 1.6 ghz, 1 mb cache, 800 mhz fsb

works better than

Pentium 4 @ 3.2 ghz, 1 mb cache, 800 mhz fsb.......

isnt it???...

but anyways its all coming down to applications in the end... some may benefit one way, some may benefit other way...

And i am now taking for granted that my 2 x 1gb ddr2 667 mhz in dual channel is in no way bottlenecking my core 2 quad @ 1333 Mhz FSB

What do u have to say?

[infra_red_dude]

Originally Posted by bikdel

Pentium Dual Core E2140 @ 1.6 ghz, 1 mb cache, 800 mhz fsb

works better than

Pentium 4 @ 3.2 ghz, 1 mb cache, 800 mhz fsb.......

isnt it???...

Well, here your analogy is flawed. You can't use this example in the context of dual channel. Coz in case of Pentium Dual Core (which is actually the Core CPU) has a different architecture. Hence, its not jus the 2 cores that matter but a lot of things. However, this is not the case with RAM in dual channel mode. So this example can't be taken.

Originally Posted by bikdel

but anyways its all coming down to applications in the end... some may benefit one way, some may benefit other way...

And i am now taking for granted that my 2 x 1gb ddr2 667 mhz in dual channel is in no way bottlenecking my core 2 quad @ 1333 Mhz FSB

What do u have to say?

Regarding whether this will bottleneck or not, its better you search some reputed sites like anandtech or tomshardware or extremetech for a performance review. Always get RAM wid speeds close to the FSB.

[bikdel]

okay...... got it........ just used the example for the sake of using it :-0
anyways im happy with the speed of my system for now.......

will go ddr 3 after it gets cheap man

[BULLZI]

thnx @devil for reminding me that point.

yup,if the two ram frequencies are different, both rams will worh in the lower frequency .

and the main difference in architecture between C2D and Dual Core:

we all know that there are instruction sets through which the processor manipulates data. these instruction sets need clock cycles to be performed.

In Dual Core, the instruction sets are performed through a couple of clock cycles.

In C2D, the instruction sets are performed through a single clock cycle.

Thats why, C2D s are lot faster when compared to Dual Core.

[ashu888ashu888]

Originally Posted by The_Devil_Himself

^^no effect you need to have the same amount of RAM with same frequency in both the channels.
And most importantly your motherboard should support dual channel RAM.I don't think many mobos which has only ddr slots support this.

THe Intel D 865 GBF mobo supports Dual Channel RAMs as it has got 4 DDR RAM slots supporting DDR 266, 333 and 400 Mhz.

I myself got 4x512 MB DDR(400) Transcend RAMs for A total of Rs. 4800/- and after plugging in the RAMs, the system is now working in Dual Channel Mode...

Wow wow...is it true?
I have a 1gb ram in one plot and 512 in another .what will be the effect.sorry i dont know the frequency.
Just Ddr not II

U can search fora s/ware known as CPU-Z wich will tell ur the Frequencies of both ur RAMs (1GB as well as the 512 MB one) but it is advisable that u either get a 1 GB DDR RAM (of the same frequency after u get to knw the frequency of ur RAM from using CPU-Z) or try and sell ur 1 GB and get 3 more 512 MB DDR RAMs as i am having 4 x 512 MB DDR(400) Transcend RAMs running in DUAL CHANNEL mode..

NOTE: U can check if ur mobo supports Dual channel and the maximum freq of RAM (like, this way it will be mentioned in ur mobo manual...---> )
"This motherboard/board supports DDR 266, DDR 333 and DDR 400 Frequency of RAM..."


Cheers n e-peace.....

[a_tif]

in single channel the memory bandwidth is 64-bit

in dual channel it is 128-bit

hence performance increase

[bikdel]

whats the percentage performance increase??

[infra_red_dude]

^^^ That is not a fixed quantity and can't be stated with accuracy. But its surely faster than single channel.

[bikdel]

okay . thats like a blind shot...

will try benchmarking though......