As AMD and Intel transitioned to higher FSB speeds, DDR-SDRAM has been hard pressed to keep pace. Figure 6-2 shows a DDR-SDRAM DIMM.īy early 2003, the original DDR-SDRAM technology was fast approaching its limits. DDR-SDRAM DIMMs use 184 pins and can be discriminated from 168-pin SDR-SDRAM and 240-pin DDR2-SDRAM memory modules by noting the number of pins and the position of the single keying notch.
If it is not labeled, you can identify the speed and other characteristics of an DDR-SDRAM DIMM by checking the item number on the module on the manufacturer web site.
#Ram memory speed ns upgrade#
If you are upgrading a system that has a limited amount of slower DDR-SDRAM and the processor can take advantage of the higher speed of PC3200 DDR-SDRAM, it often makes sense to replace the slower modules rather than simply adding the PC3200 modules.Īny system that uses DDR-SDRAM is a good upgrade candidate. Also, some motherboards don't deal well with memory of mixed speeds. Mixing faster modules with slower modules causes the faster memory to run at the speed of the slowest module installed. These premium-price modules provide no benefit unless you are overclocking a system beyond its rated speed. High-performance memory modules targeted at gamers, overclockers, and other enthusiasts are available with ratings of PC3500, PC4000, PC4200, and higher. The limited availability of PC2100 and slower forms of DDR-SDRAM is not an issue for systems that use those slower variants, because PC3200 memory is backward-compatible with slower variants. The falling price of PC3200 DDR-SDRAM modules quickly obsoleted slower forms of DDR-SDRAM, although PC2700 modules remain in limited distribution.
Similarly, DDR-SDRAM DIMMs that use DDR266 chips are labeled PC2100, those that use DDR333 chips are labeled PC2700, and those that use DDR400 chips are labeled PC3200. So, for example, a DDR-SDRAM DIMM that uses DDR200 chips transfers 8 bytes 200 million times per second, for a total bandwidth of 1,600 million bytes/second and is called a PC1600 DIMM.
#Ram memory speed ns 64 bits#
Their data path is 64 bits (8 bytes) wide. Unlike SDR-SDRAM DIMMs, which are designated by their chip speeds, DDR-SDRAM DIMMs are designated by their bandwidth. Similarly, chips that operate at 133 MHz are called DDR266 chips, those that operate at 166 MHz are called DDR333 chips, and those that operate at 200 MHz are called DDR400 chips. For example, 100 MHz chips are double-pumped to 200 MHz, and so are called DDR200 chips. The chips used to produce a DDR-SDRAM memory module, called a DIMM (Dual In-line Memory Module) are named for their operating speed. Because DDR-SDRAM costs essentially the same to produce as SDR-SDRAM, it quickly obsoleted SDR-SDRAM. DDR-SDRAM is an evolutionary improvement of standard SDRAM, which is now sometimes called Single Data Rate SDRAM or SDR-SDRAM to differentiate it. Relative to standard SDRAM, Double Data Rate SDRAM (DDR-SDRAM) doubles the amount of data transferred per clock cycle, and thereby effectively doubles peak memory bandwidth. If you are choosing between two similar processors, always choose the one with the larger L2 cache. Running a similar distributed processing application that used data sets too large to fit in the 1 MB L2 cache, the processor with the larger L2 cache was only marginally faster. That was true because the entire work unit fit within the 1 MB L2 cache, but not within the 512 KB L2 cache. For example, when we tested the ( ) client on two nearly identical processors, one with 512 KB of L2 cache and the other with 1 MB, the second processor completed work units in less than half the time required by the first. The amount of cache memory present on a processor can have a dramatic impact on performance, particularly if you work on small data sets. Modern processors have L2 cache memory sizes ranging from 128 KB to 2 MB. L2 cache is a part of the CPU package (or of the CPU substrate itself) on all modern processors, including the Intel Pentium 4 and Celeron, and the AMD Athlon 64 and Sempron. Secondary cache memory, also called Level 2 cache or L2 cache, bridges that gap with a reasonable compromise between cost and performance. L1 cache is not large enough to eliminate the speed disparity between processors and main memory.
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