1. Dual-Channel Architecture
Brad Traina
April 7, 2009

2. Memory Hierarchy

3. Physical Memory
Physical memory, also known as RAM, stores data for use by the CPU
There are many types of physical memory, the most common used today being SDRAM

4. Random Access Memory
Random Access Memory (RAM) : stored data is to be accessed at random
Any piece of data can be returned at a constant time, regardless of its physical location
RAM is volatile, meaning all information is lost when the power is shut off

5. Who Invented RAM?
In 1966, Robert Dennard invented DRAM (dynamic random access memory)
He received a patent for his idea in 1968.

6. Computer Memory
A computer's memory (RAM) is a temporary storage area for data that needs to be accessed at high speeds.
This can help programs run more efficiently.
The processor can only work as fast as data can be passed to it from the CPU.
If the CPU is waiting on data from the memory, it is not working at its full potential. The memory needs to keep up with the CPU.

7. Single-Channel Memory
Single-Channel memory is like a funnel that feeds data to the processor through a single pipe
Data is transferred 64 bits at a time
This can create a bottleneck

8. Dual-Channel Memory
With dual-channel memory it is like having two funnels feeding data through two pipes
With two channels, data can be transferred 128 bits at a time

9. Memory Controller
The memory controller manages the data flow between the processor and the memory
Data gets sent to the memory controller which decides whether to store it in memory or send it to the processor

10. Memory Controller

11. Single-Channel Memory
Single Channel memory can be though of as a one lane street.
Data needs to flow both in and out of memory on this one lane street.

12. Dual-Channel Memory
Dual-Channel memory doubles the maximum amount of data that can be transferred between the CPU and the memory
We now have a two lane road capable of sending and receiving data at the same time.

13. Peak Bandwidth
Peak bandwidth describes the maximum amount of data processed by memory in a given time period.
It is calculated by the following formula:
Memory Speed * Number of bytes transferred per channel * Number of channels

14. Performance Notice that these transfer rates are theoretical.
They are calculated assuming that a data transfer will occur each clock cycle.
In reality, no CPU or memory controller will be transferring data 100% of the time.
For this reason 100% theoretical performance increase does not translate into a 100% performance increase of your computer.

15. Synchronous Dual-Channel
For the best dual-channel memory performance you must use identically paired memory
In order for memory to be considered Identical it must have:
The same capacity
The same speed
The same latency
This setup is referred to as synchronous dual- channel. It is the standard when you think of dual-channel memory.

16. Asynchronous dual-channel
Asynchronous dual-channel memory is quite new, and provides less performance gain when compared to synchronous dual-channel
In order to use this you must have memory:
With the same speed
With the same latency
In this case the capacity of the memory does not matter

17. Triple-Channel Memory
The new intel core i7 processor supports triple channel memory.
The memory controller is now built into the processor.
It is capable of transferring 192 bits at a time

18. End

19. Resources http://en.wikipedia.org/wiki/Dual-channel_architecture
“Everything You Need to Know About Dual Channel
By Gabriel Torres
“Intel Dual-Channel DDR Memory Architecture White Paper”
By Infineon Technologies and Kingston Technology