RAM, Single Channel, Dual Channel, and Flex Channel

Single Channel, Dual Channel, and Flex Channel RAM




Overview
There is quite a bit of confusion about how dual channel memory works and what kind of ram is needed to operate in this mode. This article is based on one found on the Intel website.

What is Dual Channel
Dual channel architecture describes a technology that doubles data throughput from RAM to the memory controller. Dual-channel-enabled memory controllers utilize two 64-bit data channels, resulting in a total bandwidth of 128-bits, to move data from Ram to the CPU.

What is Flex Mode
Flex Mode describes a technology that enables dual channel operation in two differently sized ram modules running at different speeds. It enables this by matching the higher spec memory to the settings of the lower spec memory. It uses the leftover ram memory in the higher spec unit in single channel mode.

There are several types of memory configurations available for Intel chipset motherboards.

♦ Dual Channel
♦ Single Channel
♦ Flex Mode

There are several types of memory configurations available for other chipset motherboards.

♦ Dual Channel
♦ Single Channel

Dual channel (Interleaved) mode 
This mode offers the highest throughput for real world applications. Dual channel mode is enabled when the installed memory capacities of both DIMM channels are equal. Technology and device width can vary from one channel to the other but the installed memory capacity for each channel must be equal. If different speed DIMMs are used between channels, the slowest memory timing will be used.
Memory Configuration for Dual Channel Mode Dual channel mode can be achieved with two, three or four DIMMs.

 Dual Channel (Interleaved) Mode Configuration with Two DIMMs

Dual Channel (Interleaved) Mode Configuration with Three DIMMs


Dual Channel (Interleaved) Mode Configuration with Four DIMMs
Rules to Enable Dual Channel ModeTo achieve Dual Channel mode, the following conditions must be met:

♦ Matched DIMM configuration in each channel
♦ Same Density (128MB, 256MB, 512MB, etc.)
♦ Matched in both Channel A and Channel B memory channels
♦ Populate symmetrical memory slots (Slot 0 or Slot 1)

Note: Configurations that do not match the above conditions will revert to Single Channel mode.

The following conditions do not need to be met:

♦ Same brand
♦ Same timing specifications
♦ Same DDR speed

Note: Memory channel speed is determined by the slowest DIMM module populated in the system.

The following image shows the BIOS Main menu with Dual Channel configuration information:



Single channel (Asymmetric) mode
This mode is equivalent to single channel bandwidth operation for real world applications. This mode is used when only a single DIMM is installed or the memory capacities are unequal. Technology and device width can vary from one channel to the other. If different speed DIMMs are used between channels, the slowest memory timing will be used.

Memory Configuration for Single Channel Mode

Single Channel (Asymmetric) Mode Configuration with One DIMM

Single Channel (Asymmetric) Mode Configuration with Three DIMMs

At boot, the memory configuration is detected and you may see this alert message:

Maximum memory performance is achieved with equal amounts of memory installed in each channel.
Press Any Key To Continue...

This means that with the DIMMs that are currently installed, the computer is set to single channel mode but, in fact, is capable of dual channel mode. If you shut down and rearrange the DIMMs properly, you'll achieve dual channel mode.

Note: Memory channel speed is determined by the slowest DIMM module populated in the system.

The following image shows the BIOS Main menu with Single Channel configuration information:



Flex mode
This mode provides the most flexible performance characteristics. The bottommost DRAM memory (the memory that is lowest within the system memory map) is mapped to dual channel operation; the topmost DRAM memory (the memory that is nearest to the 8 GB address space limit), if any, is mapped to single channel operation. Flex mode results in multiple zones of dual and single channel operation across the whole of DRAM memory. To use flex mode, it is necessary to populate both channels.

Intel Desktop Boards based on the following chipsets support Flex Mode:

♦ X48
♦ X38
♦ Q35
♦ P35
♦ G35
♦ G33
♦ P965
♦ G965
♦ Q965
♦ Q963

Memory Configuration for Flex Mode

NOTE: The use of flex mode requires DIMMs to be installed in both channels.

The figure below shows a flex mode configuration using two DIMMs. The operation is as follows:

♦ The 512 MB DIMM in the Channel A, DIMM 0 socket and the lower 512 MB of the DIMM in the Channel B, DIMM 0 socket operate together in dual channel mode. 
 
♦ The remaining (upper) 512 MB of the DIMM in Channel B operates in single channel mode.


The following image shows the BIOS Main menu with Flex Mode configuration information:

RAM. What is interleaved memory?

RAM. What is interleaved memory?
RAM dual channel inter leaved


A basic explanation of Interleaved memory is, the memory on the motherboard is accessed as if it is one large block of memory e.g. the 2 RAM modules act like they are 1 RAM module. This reduces access times and gives an overall speed boost.

 Mixing memory types/speeds/etc will result in slower memory timing speeds (lowest common denominator) and certain functions being disabled if memory sizes are mixed. The reason for this is that memory interleaving is a sort of 'computer math trick' that allows the RAM to have faster throughput if all of the memory address' align (which means the sticks would have to be at least the same sizes). Your motherboard/chipset combination will determine what your limits are based on the memory types you put in, in other words, memory functionality (dual-channel/interleaving) is a function of the motherboard/chipset you use and not necessarily of the RAM itself. If you have 2 sticks of 4GB (2x4GB) in slots 1 and 3 (usually how it goes in dual channel) they should be of the same type (speed/latency/etc.) otherwise the RAM won't 'work' at all (won't be recognized) or the RAM will 'run' at the lowest speed of the two. Mixing the sizes in the banks (2x2GB and 2x4GB) should keep the 'dual-channel' configuration if that's an option in your chipset and the dual sticks are the same (i.e. speed), but it could depend if you will still have memory interleaving as that is an algorithm employed by the chipset manufacturer which uses 'banks of memory' (could be the entire stick or a few chunks of it).

  If you are only doing basic (not video/games) web surfing, and document editing, even some power stuff may not understand the performance difference. But if you are a gamer, like watching lot of videos, do any sort of virtualization, are an enthusiast, graphic designer, video editor, etc. then memory interleaving 'could' make a significant difference to you.

FACEBOOK SECURITY BREACH, PHISHING EMAIL FROM FACEBOOKMAIL.COM

While Facebook’s One Click feature isn’t new, it’s rarely talked about—save for confused users trying to look up whether it’s a scam. It’s a valid question, particularly in light of Facebook’s most recent security breach, wherein hackers used a bug in the platform’s code to gain access to millions of users accounts. Experts say the hack will likely lead to a rise in phishing attacks. While One Click is in fact real and not a phishing scam, it is riddled with unsafe security practices—perhaps all in the name of driving Facebook user numbers. I had sent Facebook an email to ask about when One Click was launched, and why ? I didn’t receive answers to those specific questions, but after sending an example of a One Click email to the company, a representative confirmed it came from the social network. The reporter also pointed me in the direction of Facebook’s Security Settings page, where users can confirm whether or not Facebook has sent them an email.

 That tool is a helpful one, especially since users who receive a One Click access email from Facebook are greeted by the rather suspicious-looking “security@facebookmail.com” address. The email explains that Facebook has noticed the user was having trouble logging in. The note is accompanied by a button that reads: “Log In With One Click.” Click it, and the user will be automatically logged back into Facebook. (Facebook also asks users to let the company know if the unsuccessful attempt to login did not come from them.)


Everything about the One Click method seems scammy, from the “@facebookmail.com” email suffix to the password-less entry. “Sending a single-click login link via email is bad enough but also sending that email unsolicited is an extremely poor security practice.”  Some People claims they are getting this message on their email when they have no account with that email address also. Which makes it clear that it is absolutely intended for phishing or hacking your email address or Facebook address. 

 How to stay safe, just don't click on that link that they have sent you on email address. And delete this type of message from your inbox to make sure you will never going to click on this link in future.