Let's explain a little what you will run into with memory timings. First off latency. We used the word numerous times already in this article. Latency is the time between when a request is made and when the request is answered. I.E, if you are in a restaurant for a meal, the latency would be the time between when you ordered your meal to the time you received it. Therefore, in memory terms, it is the total time required before data can be written to or read from the memory. Thus lower is better.
So what we notice on the packaging is this: 9-9-9-24 (2T) for a memory kit. What do the numbers mean ? Well this refers to CAS-tRCD-tRP-tRAS and CMD (respectively) and these values are measured in clock cycles.
CAS Latency Undoubtedly, one of the most essential timings is that of the CAS Latency and is also the one most people can actually understand. Since data is often accessed sequentially (same row), the CPU only needs to select the next column in the row to get the next piece of data. In other words, CAS Latency is the delay between the CAS signal and the availability of valid data on the data pins (DQ). Therefore, the latency between column accesses (CAS), plays an important role in the performance of the memory. The lower the latency, the better the performance. However, the memory modules must be capable of supporting low latency settings.
tRCD There is a delay from when a row is activated to when the cell (or column) is activated via the CAS signal and data can be written to or read from a memory cell. This delay is called tRCD. When memory is accessed sequentially, the row is already active and tRCD will not have much impact. However, if memory is not accessed in a linear fashion, the current active row must be deactivated and then a new row selected/activated. It is this example where low tRCD's can improve performance. However, like any other memory timing, putting this too low for the module can result in instability.
tRP tRP is the time required to terminate one one Row access and begin the next row access. Another way to look at this it that tRP is the delay required between deactivating the current row and selecting the next row. Therefore, in conjunction with tRCD, the time required (or clock cycles required) to switch banks (or rows) and select the next cell for either reading, writing or refreshing is a combination of tRP and tRCD.
tRAS Memory architecture is like a spreadsheet with row upon row and column upon column with each row being 1 bank. In order for the CPU to access memory, it must first determine which Row or Bank in the memory that is to be accessed and activate that row via the RAS signal. Once activated, the row can be accessed over and over until the data is exhausted. This is why tRAS has little effect on overall system performance but could impact system stability if set incorrectly.
Command Rate The Command Rate is the time needed between the chip select signal and the when commands can be issued to the RAM module IC. Typically, these are either 1 clock or 2.
Memory testing is a process of trial and error, find and seek the maximum. This is pretty much a sucker for your free time.
Traditional system: If you are going to overclock then increase the FSB, change the memory timings, but most of all alter memory dividers until your system won't boot. If you are not comfortable with such a thing, hey this isn't your game then. I recommend you to lower the processor's multiplier and then slightly increase the FSB with high memory timings and take it from there timings wise. For a Core i7 system: change memory multipliers/dividers in the BIOS or overclock QPI frequency and memory voltage.
G.Skill Sniper 8GB CL7 DDR3 memory review G.Skill designed another 8GB low voltage DDR3 kit (2x 4GB) that can be set at 1600 MHz yet still run a CAS latency of 7. And that is truly interesting because the denser the ICs get, the higher latency typically gets.
G.Skill 2x4GB CL7 1600 MHz Trident DDR3 review We feel that more memory is rather important, and in that trend memory manufacturers have started to increase the density of DIMM modules. Where 1 and 2GB DIMM modules have been the standard, we now see very good progress in 4 GB DIMM modules. Today we\'ll do things a little different, G.Skill designed a 8GB low voltage DDR3 kit (2x 4GB) that can be set at 1600 MHz yet still run a CAS latency of 7. And that is truly interesting because the denser the ICs get, the higher latency typically gets.
G.Skill Flare DDR3 2000 MHZ C7 AMD kit review We test and review the G.Skill Flare DDR3 2000 MHZ C7 AMD kit. These kits are optimized for AMD platforms preferably with the new six-core X6 processors, and in specific some ASUS motherboards. The kit we'll be testing today obviously comes from that series and is a 2,000MHz CL7-9-7-24 1.65V 4GB (2GBx2) DDR3 kit with its latest Flare heatsinks.
G.Skill Phoenix PRO 120GB SSD review The SSD tested today once again is the Phoenix series from G.Skill. After we tested their 100GB Phoenix SSD (which received a very positive review) G.Skill instantly requested if we would like to review the 120GB PRO model. Both drives pretty much are the same thing, same controller ... The 100GB Phoenix uses Samsung memory though but the trick is that there is 20GB extra volume space available on the new 120GB Pro (compared to the 100GB model) for nearly the same price. A new Firmware for the SandForce 1200 based controller that is inside this 120GB model simply reserves less NAND flash memory for its data-compression scheme. As a result the overall write performance could be a tiny bit slower, but only a few percent as best. It however will give you 20 GB more space to play around with at the same price. And since price per GB is everything in the land of SSDs -- this certainly is a significant for any vendor and for you as an end-user.