RAM is a basic computer component, but we don't talk about it much. If it doesn't have a rad heat sink design and RGB accessories, the RAM rarely spends a day in the sun. The CPU sets the condition in which the rest of your build runs, but you can squeeze a little more speed out of your PC with faster RAM. Clock speed and timing, or latency, determine the speed of your RAM.
ContentsFinding your RAM clock speedWhat are RAM timings?First number:CAS Latency (CL)Second number:TRCD Third number:TPRFourth number:TRASConclusionYour RAM speed can be found on the box or module through software like CPU-Z or in BIOS/UEFI. The full name of your RAM module will look like this:
DDR4 describes the generation of DDR with which the chip is compatible. The same number (2, 3 or 4) appears in the PC number, describing the same thing.
The first four-digit number, 3200 in our example, is often said to indicate the RAM clock speed in megahertz. It's actually a bit of a marketing lie, but don't feel bad:the misunderstanding is directly encouraged by PC makers and retailers. This number actually reports the data rate , measured in megatransfers per second, or 10 6 data transfer operations per second.
In DDR RAM, the actual clock speed is half the data rate – 1600 MHz, in our example, although even that is increased from the internal RAM clock speed of 400 MHz via bits. multiplicative prefetches. But since DDR transfers data twice per clock tick, the efficient It can be said that the clock speed is twice the actual clock speed. As a result, the data rate is effective the same as the apparent RAM clock speed in MHz.
The PC number, 25600 in our example, indicates the transfer rate measured in megabytes per second (MB/s). By multiplying the data rate (in megatransfers) by the width of the I/O bus (64-bit in all modern motherboards), we can determine the maximum possible transfer rate:
3200 megatransfers per second x 64 bits per transfer / 8 bits per byte =25600 MB/s
Each number independently tells you the RAM speed. But both numbers provide the same information, but in different forms.
Timings are another way to measure RAM speed. Timings measure the latency between various common operations on a RAM chip. Latency is the delay between operations. This can be considered a "waiting time". Minimum timings are set by spec, so you can read a table of the fastest possible RAM timings for each DDR spec.
We measure RAM timing in clock cycles. Retailers list times as four numbers separated by hyphens, such as 16-18-18-38. Small numbers are faster. The order of the numbers tells you their meaning.
RAM modules use a grid-based design for addressing. The intersection of row and column numbers indicates a particular memory address. Row Address to Column Address Delay (TRCD ) measures the minimum latency between entering a new row in memory and beginning to access the columns it contains. You can think of it as the time it takes for the RAM to "reach" the address. The time to receive the first bit of a previously idle row is TRCD +CL.
Row precharge time (TPR ) measures the latency involved in opening a new row in memory. Technically, it measures the latency between issuing the preload command to slow down (or close) one line and an activation command to open another line. It is often identical to the second number. The same factors affect the latency of both operations.
Line activity time (TRAS ) measures the minimum number of cycles a row must remain open to successfully write data. Technically, it measures the latency between an activation command on a line and the issuance of the precharge command on this same line or the minimum time between the opening and closing of the line. For SDRAM, TRCD modules + CL calculates TRAS .
These latencies limit the speed of your RAM. But the RAM specifications set the limit, not the physics. The memory controller that manages your RAM enforces these timings, which means they are changeable (if the motherboard allows it). You may be able to get some performance out of your RAM by overclocking and tightening the timings a few cycles.
RAM overclocking is the most temperamental of the hardware overclocking techniques, requiring the most freezes and experimentation. But faster RAM shortens the processing time of RAM-bound workloads, improving rendering speed and virtual machine responsiveness.
