dual channel memory

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Postby Sabrewings » Mon Nov 29, 2004 7:20 pm

Gem wrote:Thanks for the info Sabre.

last Q , is there anything faster than ballistix on the market?

Your link doesn't work.

I personally use Geil as my first choice in memory. The Geil Ultra Platinum series is just as fast if not faster than Ballistix.
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Postby HollowPoint69 » Mon Nov 29, 2004 7:28 pm

What about Mushkin Level II V2? Mobo.org's review showed that one to be the highest, and two sticks of it cost about 250 bucks (for some reason the dual pack is 30 dollars more expensive!).

Postby HollowPoint69 » Mon Nov 29, 2004 7:52 pm

A touch more expensive and a touch slower I believe.

Postby felony » Mon Nov 29, 2004 8:33 pm

Gem wrote:or CORSAIR XMS ?

thats what i got but i have only 1 stick and my cas is 2 3 3 6 or sumthing like that.
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Postby Rabidwerewolf » Mon Nov 29, 2004 11:38 pm

This is an older article from 2003 from OC Forums, but it should explain it dual channel memory in great detail. I pulled out one of my pc hardware and tech books, but I didn't want to spend several hours quoting and paraphrasing and all that. The article explains it pretty good though. Someone want to volunteer writing a sticky explaining dual channel memory vs single channel memory that is more up to date. I guess I could do it, but I think there are others far more qualified. Oh, here is the full article. http://www.ocforums.com/showthread.php?t=257741

[quote="Drisler at OCForums, Memory: Basics, Tweaking & Overclocking"]DDR Memory Speeds

The speed of DDR is usually expressed in terms of its "effective data rate", which is twice its actual clock speed. PC3200 memory, or DDR400, or 400 MHz DDR, is not running at 400 MHz, it is running at 200 MHz. The fact that it accomplishes two data transfers per clock cycle gives it nearly the same bandwidth as SDRAM running at 400 MHz, but DDR400 is indeed still running at 200 MHz.

Actual clock speed/effective transfer rate

100/200 MHz => DDR200 or PC1600
133/266 MHz => DDR266 or PC2100
166/333 MHz => DDR333 or PC2700
185/370 MHz => DDR370 or PC3000
200/400 MHz => DDR400 or PC3200
217/433 MHz => DDR433 or PC3500
233/466 MHz => DDR466 or PC3700
250/500 MHz => DDR500 or PC4000
267/533 MHz => DDR533 or PC4200
283/566 MHz => DDR566 or PC4500

So how do they come about those names? Well, the industry specifications for memory operation, features and packaging are finalized by a standardization body called JEDEC. JEDEC, the acronym, once stood for Joint Electron Device Engineering Council, but now is just called the JEDEC Solid State Technology Association.

The naming convention specified by JEDEC is as follows:
Memory chips are referred to by their native speed. Example, 333 MHz DDR SDRAM memory chips are called DDR333 chips, and 400 MHz DDR SDRAM memory chips are called DDR400.

DDR modules are also referred to by their peak bandwidth, which is the maximum amount of data that can be delivered per second. Example, a 400 MHz DDR DIMM is called a PC3200 DIMM. To illustrate this on a 400 MHz DDR module: Each module is 64 bits wide, or 8 Bytes wide (each byte = 8 bits). To get the transfer rate, multiply the width of the module (8 Bytes) by the rated speed of the memory module (in MHz): (8 Bytes) x (400 MHz/second) = 3,200 Mbytes/second or 3.2 Gbytes/second, hence the name PC3200
To date, the JEDEC consortium is yet to finalize specifications for PC3500 & higher modules. PC2400 was a very short lived label applied to overclocked PC2100 memory. PC3000 was not and will not ever be an official JEDEC standard.

Processors and Bandwidth

The front side bus (FSB) is basically the main highway or channel between all the important functions in the motherboard that surround the processor through which information flows. The faster and wider the FSB, the more information can flow over the channel, much as a higher speed limit or wider lanes can improve the movement of cars on a highway. As with the FSB, a low speed limit or narrower lanes will retard the movement of cars on the highway causing a bottleneck of traffic. Intel has been able to reduce the FSB bottleneck by accomplishing four data transfers per clock cycle. This is known as quad-pumping, and has resulted in an effective FSB frequency of 800 MHz, with an underlying 200 MHz clock. AMD Athlon XPs, on the other hand, must be content with a bus that utilizes different technology, one that utilizes both the rising and falling sides of a signal. This is in essence the same double data rate technology used by memory of the same name (DDR), and results in a doubling of the FSB clock frequency. That is, a 200 MHz clock results in an effective 400 MHz FSB.
Processors have a FSB data width. This data width is much like the "lanes on a highway" that go in and out of the processor. The processor uses this highway to transfer data mainly between itself and system. When the first 8088 processor was released, it had a data bus width of 8 bits and was able to access one character at a time (8 bits = 1 character/byte) every time memory was read or written. The size in bits thus determines how many characters it can transfer at any one time. An 8-bit data bus transfers one character at a time, a 16-bit data bus transfers 2 characters at a time and a 32-bit data bus transfers 4 characters at a time. Modern processors, like the Athlon XP and Pentium 4, have a 64-bit wide data bus enabling them to transfer 8 characters at a time. Although, these processors have 64-bit data bus widths, their internal registers are only 32 bits wide and they're only capable of processing 32 bit commands and instructions while new AMD64 series of processors are capable of processing both 32 bit and 64 bit commands and instructions.
When talking memory, bandwidth refers to how fast data is transferred once it starts and is often expressed in quantities of data per unit time. The peak bandwidth that may be transmitted by an Athlon XP or a Pentium 4 is the product of the width of the FSB and the frequency it runs at. To illustrate:

Athlon XP “Bartonâ€
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