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Overclocking RAM
Overclocking means setting one or more of a computer's components to run faster than the manufacturer's recommended official setting(s). A practice that should be fully researched before it is indulged in, because applying settings that are too high for a particular device can make the system unstable and prone to errors, or even damage or render it useless.
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If you increase the FSB speed of the motherboard - via the BIOS or by setting jumpers on the motherboard - you will overclock the processor, the RAM, the video card, sound card, and the IDE disk drives.
Of those components, only the processor is likely to find the increased FSB unacceptable, because it is the component that is overclocked the most if the FSB is changed from an official speed of say 166MHz to an overclocked speed of 200MHz.
Doing this can result in a significant gain in performance if the processor can operate completely normally at the the increased FSB setting. But if the stability of the processor is made erratic as a result, you won't usually be able to overclock the RAM.
For example, suppose that the processor is an Athlon XP 2800+ with a Barton core that is designed to run at 2.08GHz on a 166MHz FSB. If the motherboard supports both DDR333 and DDR400 RAM, and has DDR333 RAM installed, you could try increasing the FSB to 200MHz, which the motherboard supports because the DDR400 RAM it supports runs on a 200MHz FSB.
Doing this would overclock the DDR333 RAM to run at the speed (really the frequency) of DDR400 RAM. Most DDR333 modules made by a manufacturer of quality, such as Crucial, can be successfully overclocked to the higher speed of DDR400 RAM. But increasing the FSB would also overclock the processor to run at 2.5GHz. A twenty-five percent increase over 2GHz!
If the system runs with stability over a lengthy period, fine, you're in luck, but the chances are that the processor won't like the high speed it's running at, and you might have to decrease the FSB setting significantly (if the BIOS or the motherboard's jumpers allow a range of settings that are higher than the official setting) to make it run with stability.
The only other alternative would be to overclock the motherboard's memory bus while keeping the FSB constant so that the processor isn't being overclocked at all. But motherboards that support separate bus settings for the memory and FSB are rare. In any case, using this method of overclocking the RAM only results in a minimal gain in system performance of around 5% at most. The best gains are always achieved by increasing the FSB so that it overclocks both the RAM and the processor.
Personally, I think that the results obtained by overclocking are mostly in the mind, and, since it stresses the components beyond the tolerances they were tested for, I don't ever bother with overclocking. If you want the fastest available system, unfortunately, as usual, you have to be prepared to pay the high prices for all of the fastest, latest components.
But if you want to attempt overclocking the RAM on your system, you can use the free MemTest utility, which runs from a floppy disk (independently of the operating system), and which stresses the RAM running at a particular FSB speed in order to determine its reliability at that speed. It can be used to find out how far the RAM can be overclocked.
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Dual Channel What is it and how does it work?
Take note that the memory isn't dual channel, the platform is. In fact there is no such thing as dual channel memory. Rather, it is a memory interface composed of two (or more) normal memory modules coordinated by the chipset on the motherboard, or in the case of the Athlon64 FX and Opteron processors, coordinated by the integrated memory controller. But for the sake of simplicity, we refer to DDR dual channel architecture as dual channel memory.
The nforce2 platform has two 64bit memory controllers (which are independent of each other) instead of just a single controller like other chipsets. These two controllers are able to access "two channels" of memory simultaneously. The two channels, together, handle memory operations more efficiently than one module by utilizing the bandwidth of two modules (or more) combined. By combining DDR400 (PC3200) with dual memory controllers, the nForce2 could offer up to 6.4GB/sec of bandwidth in theory. It is also possible for DDR Dual Channel architecture to reduce system latencies and timing delays that inherently occur with one memory module. For example, one controller reads and writes data while the second controller prepares for the next access, hence, eliminating the reset and setup delays that occur before one memory module can begin the read/write process all over again. Think of it like two relay runners. The first runner runs one leg while the second runner sets up and prepares to receive the baton smoothly and carry on the task at hand without delay.
However, this extra bandwidth produced by dual channel cannot be fully utilized by the Athlon XP and Duron family (K7) of processors. The system bus on an Athlon XP doesn't’t know the difference between Dual Channel and a TV Channel. Data(bandwidth) will reach these processors no sooner than the system bus (FSB) allows them, and the processor therefore largely cannot derive an advantage from memory operating faster than DDR266 when operating on a 133/266Mhz FSB, DDR333 with a 166/333Mhz FSB or DDR400 at 200/400Mhz FSB even in single channel mode. Visualize a four lane highway, symbolizing your Dual Channel configuration. As you go along the highway you come up to a bridge that is only 2 lanes wide. That bridge is the restriction posed by the dual-pumped AMD FSB. Only two lanes of traffic may pass through the bridge at any one time. That's the way it is, with the K7 processors and Dual Channel chipsets. In case you're wondering, the K in K7 stands for Kryptonite, later changed to Krypton to avoid copyright infringement. Yes, that very same fictional element from comic books that could bring the otherwise all-powerful Superman (Intel ) to his knees. Cool eh? how K endured in the names of various AMD chips for several years and even in the ones to come.
Intel's P4 architecture, in contrast, is designed to exploit the increased bandwidth afforded by dual channel memory architectures. The quad pumped P4 FSB seemed like drastic overkill in the days of single channel SDR memory, but is paying handsome dividends in today's climate of dual channel DDR memory subsystems. This is one lasting and productive legacy of Intel's RDRAM efforts. As implemented on the P4 RDRAM was also dual channel architecture, and mandated the quad-pumped FSB for its extra bandwidth to be exploited. This factor continues to serve the P4 well in the dual channel DDR era we are currently in, and allows P4's greater memory performance than all other PC platforms, save the new AMD Athlon 64 FX with all its new bells and whistles.
The Athlon 64 FX processor has a fully integrated DDR Dual Channel memory controller providing a 128-bit wide path to memory and therefore eliminating the need for a Dual Channel interface on the motherboard which traditionally was always located in the northbridge. Although the P4 (800fsb variety) and the A64 FX, both share the same theoretical peak memory bandwidth of 6.4GB/sec, the Athlon FX realizes significantly more throughput due mainly to it’s integrated memory controller. Even so, it still suffers from the required use of registered modules which are slower than regular modules, in terms of subsystem latency. The upcoming Athlon 64 / A64 FX processors designed for Socket 939 will be free from this major drawback and will also feature Dual Channel memory controllers.
