Home > Sample chapters
- By Darril Gibson
- 12/15/2012
The answer, unfortunately is not definitive. But, because of no strict standardization enforcement it may not work. I’d say better to order DDR3 if that is what originally came. I just bought a New HP a1310y Desktop and replaced its memory from 256 MB DDR2-4200 533 MHz with 2 modules of 512 MB DDR2-4200 533 MHz. (Total Memory 1 GB).
Contents×- RAM
Exam 220-801 objectives in this chapter:
1.2 Differentiate between motherboard components, their purposes, and properties.
CPU sockets
1.3 Compare and contrast RAM types and features.
Types
DDR
DDR2
DDR3
SDRAM
SODIMM
RAMBUS
DIMM
Parity vs. non-parity
ECC vs. non-ECC
RAM configurations
Single channel vs. dual channel vs. triple channel
Single sided vs. double sided
RAM compatibility and speed
1.6 Differentiate among various CPU types and features and select the appropriate cooling method.
Socket types
Intel: LGA, 775, 1155, 1156, 1366
AMD: 940, AM2, AM2+, AM3, AM3+, FM1, F
Characteristics
Speeds
Cores
Cache size/type
Hyperthreading
Virtualization support
Architecture (32-bit vs. 64-bit)
Integrated GPU
Cooling
Heat sink
Fans
Thermal paste
Liquid-based
Exam 220-802 objectives in this chapter:
4.2 Given a scenario, troubleshoot common problems related to motherboards, RAM, CPU and power with appropriate tools.
Common symptoms
Unexpected shutdowns
System lockups
Overheating
Ddr2 Slot Colors
RAM
When technicians are talking about a computer’s memory, they are primarily talking about random access memory (RAM). RAM is used for short-term storage of applications or data so that the processor can access and use this information. In contrast, computers use hard drives for long-term storage of data.
Most RAM is volatile. This doesn’t mean that it’s explosive; it means that data in RAM is lost when power is removed.
As an introduction, the following list identifies commonly used types of RAM. All of these types of RAM are volatile.
Dynamic RAM (DRAM). Dynamic refers to how bits are stored in an electrical component called a capacitor. The capacitor holds the bit as a charge, but the capacitor needs to be regularly refreshed to hold the charge. This configuration uses very few components per bit, keeping the cost low, but the constant refresh reduces the speed.
Synchronous DRAM (SDRAM). SDRAM is synchronized with a clock for faster speeds. Almost all primary DRAM used in computers today is SDRAM, but it’s often listed as DRAM to avoid confusion with SRAM.
Static RAM (SRAM). Static RAM uses switching circuitry instead of capacitors and can hold a charge without a constant refresh. It requires more components per bit so it is more expensive, but due to how the switching works, it is quicker than DRAM. Due to the speed, SRAM is commonly used for CPU cache (described later in this chapter) but is rarely used as the primary RAM because of its cost.
Flash memory is very popular, but not as the primary RAM used in a system. USB flash drives, solid-state drives (SSDs), and memory cards used in cameras and other mobile devices all use flash memory. Flash memory is used for BIOS in many motherboards. Unlike DRAM and SRAM, flash memory is not volatile and retains data without power.
Double Data Rate SDRAM
While the original SDRAM versions were quick and efficient for their time, manufacturers have steadily improved them. Double data rate (DDR) is one of the improvements and is used in almost all SDRAM. As a reminder, SDRAM is tied to a clock, and when the clock ticks, data is transferred.
SDRAM uses only the leading edge for the clock. However, each of the DDR SDRAM versions uses both the leading and trailing edge of the clock. This is often called double pumping. Figure 3-1 compares the two over two cycles of a clock. You can see that SDRAM has two clocks from these cycles and that DDR has four clocks from the same two cycles.
Figure 3-1. SDRAM compared with double-pumping DDR.
The following list provides an overview of the different DDR versions:
Double Data Rate (DDR) SDRAM. DDR uses double pumping to double the data rate of SDRAM.
DDR2. DDR2 doubles the data rate of DDR. In addition to double pumping, it modifies the way that data is processed and can transfer twice as much data as DDR SDRAM.
DDR3. DDR3 doubles the data rate of DDR2. It uses double pumping and further modifies the way that data is processed. It can transfer four times as much data as DDR and eight times as much data as SDRAM.
DDR4 isn’t included in the objectives, but it is on the horizon as a replacement for DDR3. It’s expected to double the speed of DDR3.
DIMMs and SODIMMs
RAM comes on cards plugged into the slots in the motherboard. They are smaller than expansion cards, and technicians commonly call memory cards sticks. The two most common types of memory sticks are:
Dual in-line memory module (DIMM). A DIMM is the circuit board that holds the memory chips.
Small outline dual in-line memory module (SODIMM). SODIMM chips are smaller and are used in smaller devices such as laptop computers and some printers.
Figure 3-2 shows a DIMM (top) and a SODIMM (bottom).
DIMMs and SODIMMs have a different number of pins depending on the type used.
DDR SDRAM DIMM: 184 pins
DDR2 SDRAM DIMM: 240 pins
DDR3 SDRAM DIMM: 240 pins
DDR SDRAM SODIMM: 200 pins
DDR2 SDRAM SODIMM: 144 or 200 pins
DDR3 SDRAM SODIMM: 204 pins
Single Channel, Dual Channel, and Triple Channel
Many motherboards and CPUs support single-channel, dual-channel, and triple-channel memory architectures. Each single channel represents a separate 64-bit line of communication that can be accessed independently. With dual channel, the system can access 128 bits at a time; triple channel gives it access to 192 bits at a time.
Using dual and triple channels provides an additional performance enhancement to DDR, DDR2, and DDR3, in addition to double pumping and other enhancements provided by the DDR versions. If you use a dual-channel motherboard with DDR3, it doubles the throughput of DDR3, providing 16 times more data throughput than SDRAM.
If you are upgrading a computer’s memory, it’s important to understand these channels. You can purchase DIMMs in matched pairs. Where you install each DIMM determines how many channels your system will use and can affect the performance of RAM.
Single Channel vs. Dual Channel
Dual-channel motherboards are very common. If you look at a dual-channel motherboard, you see that it has four memory slots, two slots of one color and two slots of another color. Figure 3-3 shows a diagram of four memory slots labeled for a motherboard using an Intel-based CPU. Slots 1 and 3 are one color, and slots 2 and 4 are another color.
Figure 3-3. Intel-based DDR slots (S), banks (B), and channels (C).
Slots: Each slot can accept one DIMM.
Banks: A bank is composed of two slots. In Figure 3-3, Bank 0 includes slots 1 and 3 and these two slots are normally blue. Bank 1 includes slots 2 and 4 and these slots are normally black. This is standard for Intel CPU-based motherboards.
Channels: Each channel represents a separate 64-bit communication path. Slots 1 and 2 make up one channel, and slots 3 and 4 make up the second channel.
You can install a single DIMM in slot 1, and the system will have a single-channel RAM. You can purchase DIMMs in matched pairs, and it’s important to know in which slots to install them. For the best performance, you should install matched DIMMs in the same bank. Looking at Figure 3-3, you should install the matched pair of DIMMs in slots 1 and 3 (Bank 0), leaving slots 2 and 4 empty. The system will take advantage of the dual-channel architecture by using two separate 64-bit channels.
What happens if you install the DIMMs in slots 1 and 2 instead? The system will still work; however, both DIMMs are installed in channel 1, so the system will work with only a single channel. RAM will be about half as fast as it could be if it were installed correctly to take advantage of the dual channels.
Figure 3-3 and the previous explanation describe the color coding, banks, and channels for Intel-based CPU motherboards. However, most motherboards designed for AMD CPUs are organized differently, as shown in Figure 3-4. On these motherboards, slots 1 and 2 make up Bank 0, and slots 3 and 4 make up Bank 1. Channel 1 includes slots 1 and 3, and channel 2 includes slots 2 and 4.
Figure 3-4. AMD-based DDR slots (S), banks (B), and channels (C).
While this can be confusing between different motherboards, the good news is that most motherboard manufacturers use the same color for each bank. For Intel-based motherboards, Bank 0 includes slots 1 and 3, and these will be the same color (often blue). Bank 1 includes slots 2 and 4, and they will be a different color (often black). AMD motherboards also use one color for Bank 0 (slots 1 and 2) and another color for Bank 1 (slots 3 and 4).
Triple Channel
On some motherboards, you see six DIMM slots instead of four. This indicates the system supports triple-channel memory usage. Table 3-1 shows the configuration of the slots, banks, and channels for a motherboard using triple-channel RAM.
Table 3-1. Triple-Channel DIMMs
Slots | Banks | Channels |
Slot 1 | Bank 0 | Channel 1 |
Slot 2 | Bank 1 | Channel 1 |
Slot 3 | Bank 0 | Channel 2 |
Slot 4 | Bank 1 | Channel 2 |
Slot 5 | Bank 0 | Channel 3 |
Slot 6 | Bank 1 | Channel 3 |
Slots in each bank are commonly the same color, so you might see a motherboard with Bank 0 slots (slots 1, 3, and 5) all blue and with Bank 1 slots all black.
Triple-channel DIMMs are sold in matched sets of three, similar to how dual-channel DIMMs are sold in matched pairs. When you install triple-channel DIMMs, you should install the matched set in the same bank. For example, if you bought one set, you’d install it in slots 1, 3, and 5.
Single Sided vs. Double Sided
You’d think that single-sided and double-sided RAM refers to how many sides of a DIMM have chips. That makes sense, but it’s not entirely accurate. Instead, single sided or double sided refers to how a system can access the RAM.
In double-sided RAM, the RAM is separated into two groups known as ranks, and the system can access only one rank at a time. If it needs to access the other rank, it needs to switch to the other rank. In contrast, single-sided (or single-rank) RAM is in a single group; the system can access all RAM on the DIMM without switching.
If you have a DIMM with chips on only one side, it is most likely a single-sided (single-rank) DIMM. However, if it has chips on both sides, it can be single rank, dual rank, or even quad rank. You often have to dig into the specs to determine how many ranks it is using.
Usually, you’d think that double is better than single, but in this case, more rank is not better. Switching back and forth between ranks takes time and slows down the RAM. Single-sided RAM doesn’t switch, and if all other factors are the same, single-sided RAM is faster than double-sided RAM.
Ddr2 Slot Colorado Springs
RAM Compatibility and Speed
An important point about DDR, DDR2, and DDR3 is that they aren’t compatible with each other. You can’t use any version in a slot designed for another type. For example, you can use DDR3 DIMMs only in DDR3 slots. From a usability perspective, that’s not so great, but if you’re trying to remember which types are compatible, it’s a lot easier. You can’t mix and match them.
Figure 3-5 shows a comparison of the keyings of DDR, DDR2, and DDR3, with a dotted line as a reference through the middle of each one. You can see that the notched key at the bottom of the circuit card is different for each. The standards aren’t compatible, and this keying prevents technicians from inserting a DIMM into the wrong slot.
Speeds
Some RAM is faster than other RAM, and with faster RAM you often see faster overall performance. As you’d expect, faster RAM is more expensive. If you’re shopping for RAM, you want to ensure that you buy exactly what you need. This includes the correct DDR version, the correct number of channels if your motherboard supports multiple channels, and the correct speed.
The speed of RAM is expressed as the number of bytes it can transfer in a second (B/s) or, more commonly, as megabytes per second (MB/s). However, the speed of most RAM isn’t listed plainly. Instead, it’s listed using standard names and module names such as DDR3-800 or PC3-12800, respectively. These names indicate their speed, but not directly. If you need to shop for RAM, you need to understand these names and how they relate to the speed.
You can calculate the overall speed of any SDRAM DDR type by using a specific mathematical formula for that type. The formula includes the speed of the clock (Clk), a clock multiplier (Clk Mult) for DDR2 and DDR3, and doubling from double pumping (DP). The speed is calculated for a single channel, which is 64 bits wide, and then converted to bytes by dividing it by 8. The following formulas show how to calculate the speed of each of the DDR versions by using a 100-MHz clock:
DDR speed calculation:
Clk x 2 (DP) x 64 (bits) / 8 (bytes)
100 MHz x 2 x 64 / 8 = 1,600 MB/s
DDR2 speed calculation:
Clk x 2 (Clk Mult) x 2 (DP) x 64 (bits) / 8 (bytes)
100 MHz x 2 x 2 x 64 / 8 = 3,200 MB/s
DDR3 speed calculation:
Clk x 4 (Clk Mult) x 2 (DP) x 64 (bits) / 8 (bytes)
100 MHz x 4 x 2 x 64 / 8 = 6,400 MB/s
Table 3-2 shows how these speeds relate to the different naming conventions used with DDR types. You can see that the standard name is derived from the clock, the clock multiplier, and double pumping. For example, DDR3 uses a 4-times multiplier and double pumping. Therefore, it’s eight times faster than SDRAM. The standard name is derived by multiplying the clock by 8. The module name is a little more cryptic, but if you calculate the speed by using the clock, you can see that the PC name indicates the calculated speed in MB/s. Also, you can see that the names include the version (DDR, DDR2, or DDR3).
Table 3-2. DDR Standard Names and Module Names
100 MHz | 166 2/3 MHz | 200 MHz | |
DDR Standard Name DDR Module Name | DDR-200 PC-1600 | DDR-333 PC-2700 | DDR-400 PC-3200 |
DDR2 Standard Name DDR2 Module Name | DDR2-400 PC2-3200 | DDR2-667 PC2-5300 PC2-5400 | DDR2-800 PC2-6400 |
DDR3 Standard Name DDR3 Module Name | DDR3-800 PC3-6400 | DDR3-1333 PC3-10600 | DDR3-1600 PC3-12800 |
Each DDR version supports multiple clock speeds, and each newer version supports faster clocks. Some of the clock speeds supported by different DDR versions are as follows:
DDR: 100, 133 1/3, 166 2/3, and 200 MHz
DDR2: 100, 133 1/3, 166 2/3, 200, and 266 2/3 MHz
DDR3: 100, 133 1/3, 166 2/3, 200, 266 2/3, and 400 MHz
A key consideration when purchasing RAM is to ensure that the RAM speeds are supported by the motherboard. If the speeds don’t match, the motherboard defaults to the slower speed. For example, if your motherboard has a 100-MHz clock and you install PC3-12800 RAM, the RAM will run at 100 MHz instead of 200 MHz. It still works, but you won’t get the benefit of the higher-speed RAM.
Compatibility within Banks
In addition to matching the RAM speed with the motherboard speed, you should also match the RAM speed within banks when using dual-channel and triple-channel configurations. If one DIMM in a bank fails, you should replace both with a matched set. However, if you have to replace the failed DIMM with a spare, look for a spare that uses the same speed.
For example, if Bank 0 currently has two PC3-12800 sticks and one fails, you should replace the failed stick with a PC3-12800 stick. PC3-12800 uses a 200-MHz clock. If you replaced it with a PC3-6400 (designed for a 100-MHz clock), both sticks would run at the slower speed or revert to single channel.
Shopping for RAM
When shopping for RAM, you need to determine the clock speed of your computer and then determine the DDR name. You can boot into BIOS, as shown in Chapter 2, “Understanding Motherboards and BIOS,” to identify the clock speed used by RAM and then plug it into the formula to determine the standard name and module name.
If you have access to the Internet, there’s an easier way. You can go to one of the memory sites, such as Crucial.com or Kingston.com, and use one of their tools. You can enter the make and model of your computer, and the tool will tell you what memory is supported. Crucial.com also has an application that you can download and run to identify your motherboard, the type and speeds of supported RAM, how much RAM is installed, and recommendations for upgrading the RAM. Another tool that can help is CPU-Z (described at the end of this chapter).
Parity and ECC
Desktop systems rarely need extra hardware to detect or correct memory errors, but some advanced servers need this ability. The two primary error-detection technologies are parity and error correction code (ECC). When shopping for RAM on desktop systems, you’ll almost always buy non-parity and non-ECC RAM.
Parity works by using 9 bits for every byte instead of 8 bits. It sets the ninth bit to a 0 or a 1 for each byte when writing data to RAM. Parity can be odd parity or even parity, referring to odd and even numbers.
Odd parity is common, and when used, it ensures that the 9 bits always have an odd number of 1s. For example, if the 8 data bits were 1010 1010, it has four 1s. Four is an even number, so the parity bit needs to be a 1. Whenever data is written to RAM, the parity bit is calculated and written with each byte.
When the data is read, the system calculates the parity from the 9 bits. If it ever detects an even number of 1s, it knows there is an error, meaning that the data isn’t valid and should not be used. Parity can’t fix the problem; it just reports the error.
ECC RAM uses additional circuitry and can detect and correct errors. This extra circuitry adds significantly to the cost of the RAM and should be purchased only when necessary. For example, spacecraft that might be exposed to solar flares commonly use ECC RAM. Additionally, some high-end scientific and financial servers need it to ensure that the data in RAM remains error-free.
Rambus and RDRAM
Another type of DRAM is Rambus DRAM (RDDRAM). More commonly, you see it referred to as Rambus, Rambus DRAM, or RDRAM. RDRAM is not compatible with any of the DDR versions and is rarely used.
The circuit boards are called Rambus in-line memory modules (RIMMs) instead of DIMMs. When installing RDRAM, you must install it in pairs. In some cases, only one circuit card has memory and the second circuit card in the pair is needed to complete the circuit. The second card is called a continuity RIMM (CRIMM).
RDRAM generates quite a bit of heat. To dissipate the heat, the chips are covered with a piece of metal acting as a heat sink or heat spreader. This makes them easy to identify because DDR SDRAM is not covered with metal.
This chapter is from the book
Related resources
DDR2 Vs. DDR3 will be the DDR RAM(Random Access Memory) variations where DDR3 is a more sophisticated version and is empowered with much more capabilities like high data transfer rate, low power consumption, memory reset choices, more memory, etcetera. Nevertheless, the principal difference lies inside the information speed where DDR3 provides double the rate provided by DDR2.
With the development of technologies, the quicker versions of memories have been developed like DDR (Double Data Rate) memories. The major theory behind the DDR memories is that by employing row speech into the processor, a high number of bits are all obtained simultaneously within the processor.
There are many techniques used to raise the rate of the little transfer from hooks into the processor. The information is transported to the rising and falling edges of the clock; this is why these memories are referred to as Double Data Rate memory. Keep reading Colorfy’s article!
See also:
Table of Contents
Ram DDR2 vs DDR3 Definition
SaleBestseller No. 1Corsair Vengeance LPX 16GB (2x8GB) DDR4 DRAM 3200MHz C16 Desktop Memory Kit - Black
Bestseller No. 4OLOy DDR4 RAM 16GB (2x8GB) 3200 MHz CL16 1.35V 288-Pin Desktop Gaming UDIMM (MD4U0832160BJ0DA)Ddr2 Slot Coloring Pages
Bestseller No. 6OLOy DDR4 RAM 16GB (2x8GB) Warhawk Aura Sync RGB 3200 MHz CL16 1.35V 288-Pin Desktop Gaming UDIMM (MD4U0832160BE0DA)What Is DDR2?
The DDR2 is the next version of the DDR (Double Data Rate) memories. These variations of this Random Access Memory was designed to reach a high data rate for its block-transferring. It can transfer information in the clock speed of 400 to 1066 Mhz.
The DDR two variant is the successor of the DDR in which the principal change is put on the operational frequency of the RAM chip and prefetch buffer along with also the amount of both of those parameters are increased. A prefetch buffer is a four-piece of memory cache, resides at the RAM chip of DDR2. The buffer is employed in the RAM processor for prepositioning the little from the data bus as quickly as possible.
DDR2 is a 240-pin DIMM structure that works at 1.8 volts. These DIMMs are made up of those one or more than one RAM processor in one board linked to the motherboard. The voltage of this DDR2 is decreased from the antecedent DDR technologies to get rid of the heat impact.
DDR uses 144 pin DIMM designs and works in the voltage of 2.4 volts. There’s not any compatibility between the DDR2 and DDR, as both utilize different motherboard socket and also DIMM keys.
What Is DDR3?
DDR3 is the advanced version of the DDR2 that has improved the prefetch buffer to 8 bits and the working frequency around 1600 Mhz. On the other hand, the sum of power has decreased to 1.5 volts, which also reduces the heat effect of this high frequency. The pin design of DDR3 also has 240 pins, but these cannot be utilized from the motherboard RAM of DDR2 due to the different notched key.
In DDR3 there’s an exceptional choice available for draining the memory via a software reset activity, i.e., memory reset. The memory reset alternative makes sure that the memory has been drained and vacant after rebooting the machine.
Benefits of DDR2 Vs DDR3 Ram
Ddr2 Slot Colorado
Higher bandwidth functionality, efficiently up to 1600 MHz: The principal advantage of DDR3 comes in the higher bandwidth made possible by DDR3’s eight pieces of massive prefetch buffer compared to DDR2’s 4-bit prefetch buffer or DDR’s 2-bit buffer.
DDR3 modules may transfer information in the sufficient clock speed of 800-1600 MHz with both falling and rising edges of a 400-800 MHz I/O clock. In comparison, DDR2’s current selection of robust data transfer rate is 400-800 MHz utilizing a 200-400 MHz I/O clock, and DDR’s scope is 200-400 MHz based on a 100-200 MHz I/O clock.
Greater performance at reduced power (longer battery life in notebooks ): DDR3 memory promises a power consumption reduction of 30% compared to current business DDR2 modules because of DDR3’s 1.5-V provide voltage compared to DDR2’s 1.8 V or DDR’s 2.5 V.
- Improved low power features
- Improved thermal layout (cooler)
Disadvantages of ddr2 and ddr3
DDR3 generally has greater CAS latency: While the common latencies for a JEDEC DDR2 apparatus were 5-5-5-15, the conventional latencies to the more recent JEDEC DDR3 apparatus are 7-7-7-20 for DDR3-1066 and 7-7-7-24 for DDR3-1333. DDR3 latencies are numerically higher since the clock cycles they’re measured are briefer; the real-time period is usually equivalent to or lower than DDR2 latencies.
Additionally, while all these are the criteria, manufacturing processes tend to improve with time. Finally, DDR3 modules will probably have the ability to operate at lower latencies compared to JEDEC specifications. It’s likely to locate DDR2 memory, which is quicker than the typical 5-5-5-15 rates, but it will take some time for DDR3 to collapse beneath the JEDEC latencies.
What is the Difference Between ddr2 v ddr3 RAM?
In the ddr2 ram vs ddr3 table, we can observe that DDR3 RAM provides better performance while consuming significantly less electricity.
The difference in clock rate and maximum transfer speed numbers seem impressive on paper. However, in reality, DDR3 RAM is just two to 10 percent faster than DDR2 RAM for most real-world software (based upon your hardware specification and utilization ).
Read also:Best RAM 2020: the top memory for your PC
ddr2 and ddr3 Conclusion
DDR2 is the earlier version and is obsolete technology, also DDR3 is a later edition of this DDR in which DDR3 has been improved and provides more features like an increased storage area, very low power consumption, platform flexibility.
Video: How to Identify RAM DDR1, DDR2, DDR3 and DDR4 from Motherboard Slots #170
Last update on 2020-12-19 / Affiliate links / Images from Amazon Product Advertising API