If you want a RAM upgrade that is better than the rest, you should look at the key RAM specs to see if they will give you the performance and value for your money that you need. If you’ve built a PC or played video games, you may have seen a C16 or C18 RAM rating on the RAM module. This is a key feature.
Don’t know what to think? The “C” in C16 or C18 stands for Column Access Strobe (CAS) latency, which affects how quickly memory can be accessed. Another thing to consider is which RAM upgrade will give you the best performance and value.
This helpful overview of C16 and C18 RAM will explain what memory timings and latency are and how they affect how fast your computer works for people who don’t know much about them.
What is C16 RAM?
C16 RAM is a type of synchronous DRAM that takes 16 clock cycles between the request for RAM data and its execution.
The “C” in C16 stands for CL or CAS, which stands for the module’s Column Address Strobe latency. CAS latency measures how long it takes for data to be ready after a read command. It’s easy to see that this time gap should be as short as possible to improve the speed and performance of the computer. So, when you compare C16 and C18, you are comparing the difference in latency, measured in clock cycles.
Asynchronous RAM has memory timing measured in nanoseconds, while the CPU clock controls synchronous RAM’s external pin interface. This means that the clock frequency is also a factor in how fast a C16 RAM module is. If you put the same C16 RAM module into a computer with a different clock rate, the overall speed can be very different.
There Are Many Different Memory Banks in C16 RAM
The chips in this volatile memory of C16 SDRAM are organized into many memory banks, each of which contains rows and columns of storage units. A single read or write operation in synchronous RAM typically only uses one bank at a time. The memory bank format is established by the memory controller and the placement of the memory slots on the motherboard. In contrast, the memory bank size is established by the memory bus width.
What is C18 RAM?
C18 RAM is a type of synchronous DRAM with a latency of 18 clock cycles for the Column Address Strobe. We can also talk about CAS18, CL18, or CAS 18 timings. Basically, 18 clock cycles are needed from the time a memory operation is requested until the RAM completes it. As a result, the time it takes to execute the transfer of data from the RAM to the CPU after an instruction from the memory controller is at least two clock cycles longer than it is for C16 RAM. Read; Nvidia GeForce GTX 980MX: Is It a Good Graphics Card?
Since C18’s RAM requires more clock cycles to process a memory request, its performance lags behind C16. When assessing RAM performance, latency is only one factor.
C18 RAM is a Type of SDRAM
C18 RAM is a type of synchronous dynamic random-access memory, as is C16 RAM (SDRAM). This type of modern RAM was made in the 1990s. It has synchronous interfaces, which means that input control signals are only read when the clock input starts to rise.
The clock signal works by switching between high-frequency and low-frequency states. This helps the memory controller and memory’s integrated circuits work together. This control, which looks like a metronome, tells the RAM how to handle incoming commands. Each time the clock goes around, the RAM finishes tasks it has already started and gets new commands.
SDRAM technology is standardized by JEDEC and is widely used because it can transfer data faster and support multiple computations at the same time while keeping them all in sync.
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What’s the Difference Between C16 and C18 RAM?
The main difference between C16 and C18 RAM is that memory requests take two clock cycles longer to process in C18. This means that C16 RAM is faster than C18 RAM and has less latency.
The difference in latency is caused by the way the integrated circuits that make up the memory chips in the module are made and how they work. As microelectronic parts that can break, they need a certain amount of time to make electrical signals, switch between states, and charge their capacitors. These functions slow down the RAM, but they are necessary for commands to be carried out correctly and for data to be kept safe.
C16 vs C18 RAM: A Side-by-Side Comparison
|C16 RAM||C18 RAM|
|What it is||Memory module||Memory module|
|Primary Use||Storage of temporary system files||Storage of temporary system files with an additional registry|
|Influential Developers||Samsung, Hyundai, SK Hynix, Micron Technology, Nanya Technology||Samsung, Hyundai, SK Hynix, Micron Technology, Nanya Technology|
|Technologies Influenced||DDR SDRAM||DDR SDRAM|
CAS Latency is only part of how C16 and C18 RAM time their memories.
The CAS latency is one of four parameters that describe how fast SDRAM works. Among the other factors are:
- tRCD: delay from row address to column
- tRP: row pre-charge time
- tRAS: row active time
- Command rate
All these timings, including the CAS latency, are given in terms of clock cycles. The memory timings are written as numbers in the format CAS-tRCD-tRP on a RAM module. There may also be the command rate.
When you look at all of these parameters together, you can get an idea of how slow the RAM clock is. The RAM will work faster if each number is lower.
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CAS Latency and Memory Clock Frequency are both important.
Even though the CL rating gives you an idea of the latency of the RAM, the memory clock frequency and memory timings determine the actual latency and system performance.
To know if a C16 RAM module will be faster than a C18 RAM module, you have to look at the clock frequency. The clock’s rate and the length of a clock cycle are both set by the clock’s frequency. The clock cycles are much faster than the transfer rates usually given for SDRAM with a double data rate.
C16 vs C18: Similarities and Differences
- RAM types C16 and C18 are both types of volatile memory.
- The CPU uses both types of RAM to store temporary files and work data for operating system programs.
- SDRAM includes both C16 and C18 RAM.
- A memory controller runs both C16 and C18 buffered RAM.
- The CPU uses both kinds of RAM.
- C16 RAM responds to data requests faster than C18 RAM by two clock cycles.
- Because of how their microcircuits work, these two types of RAM may have different latency times.
What do you do with C16 RAM?
C16 RAM can be used for many programs that need a lot of memory, such as:
- Video editing
- Workstations for digital audio
C16 RAM reads and writes with less latency than C18 RAM, which gives it a noticeable speed and performance boost. But C16 RAM is not the RAM with the lowest latency. The RAM with the lowest latency is the 3200 MHz C14 RAM module, made by the Taiwanese company G.Skill.
C16 vs C18: RAM Frequency is Also a Consideration
RAM frequency refers to the rate at which your RAM functions. This is the maximum number of cycles or mega transfers it can perform in one second. RAM frequency is measured in megahertz (MHz) and is usually specified in the RAM specification (e.g. DDR4-3200).
The most widely available RAM frequencies are in the 4266 MHz range. This means that the RAM completes its cycles faster and can thus handle more data.
Another issue is that the CPU becomes a rate-limiting element at certain RAM speeds and simply cannot process the data at the speed provided by the RAM. This means that high-frequency RAM will no longer help your system beyond a certain point.
Does C18 RAM Need to Be Upgraded?
Different people have different ideas about whether or not upgrading your C18 RAM will make a noticeable difference in how fast your computer works. The effect of increasing RAM size, rank, and memory channels will be bigger. If you only look at latency or memory timings, there aren’t likely to be any gains from upgrading RAM for everyday computing.
C16 vs C18 RAM: 6 Facts You Need to Know
- CAS latency is the time between giving a column address and getting the data. The CAS latency for DDR RAM ranges from 10 to 15 nanoseconds.
- Between the request for RAM data and its execution, there is a delay of 18 clock cycles in C16 RAM. This is called latency.
- Between the request for RAM data and its execution, there is a delay of 16 clock cycles in C18 RAM.
- Both C16 RAM and C18 RAM are SDRAM.
- The absolute latency of RAM is based on four factors, each measured in clock cycles. CAS latency is only one of these four factors.
- RAM frequency and latency are important to how well a RAM module works.
Final Thoughts of C16 vs C18 RAM
When looking at RAM modules for an upgrade, CAS latency should be taken into account, but this number can’t be used by itself. You should look at the RAM frequency, the system’s clock frequency, and the CL. Other things, like the size of the RAM and the number of available channels, can also make a big difference in how fast and well the system works.
C16 vs C18 RAM: FAQs
What is CAS latency?
Column Address Strobe (CAS) is the delay between a read command and the data being shown. This delay is measured in clock cycles.
What is tWR?
tWR stands for Write Recovery time. This latency parameter measures the number of clock cycles between when data is written and when a pre-charge command is sent. This must be done to make sure that all of the data in the buffer is written to the memory core.
What is tRAS?
Row Active Time, or tRAS, is the time between a bank active command and a pre-charge command.
What is tRCD?
The Row Address to Column Address Delay, or tRCD, is another measure of latency. It counts the clock cycles between a currently running command and the read/write command.
What is tWTR?
Internal Write Read Command Delay, or tWTR, is the time that passes between the end of a write operation and the start of a read operation.