Best FSB memory ratio

**Holt** · 02-07-2009

Hello,

I wondered if the ratio FSB: DRAM has an impact on performance or was important to look at the frequency?

I did a slight O / C my E6420 2.13 at 2.4 in the amount the FSB to 300 and I put my DDR2-800 to DDR2-960 is thus a frequency of 480 and a ratio FSB: DRAM to 5:8. Are there better settings?

Thank you

**lorenz** · 02-07-2009

In general it is better to be synchronized. Otherwise the best bench in 1:1 and 5:8 and compare ...also performance is depends on your hardware capability..

**Omari** · 02-07-2009

You can try FSB memory ratio is this way
[1:1]
[5:4]
[3:2]
[sync mode]

FSB/Memory ratio is also a function of overclocking it can manage the ratio between the CPU and RAM, eg. if the ratio is 1 his means that if you put in 200 for the CPU fsb you ora a frequency of 200 for your ram, if you set 0.5 for the 200 cpu and 400 for the ram ... etc

**Darshan22** · 02-07-2009

To achieve synchronous operation, there is usually a Memory Frequency or DRAM ratio setting in the bios of your system that will allow you to manipulate the memory speed to a either a percentage of the FSB (ie 100%) or a fraction (or ratio) ie N / N where N is any integer available to you. If you want to run memory at non 1:1 ratio speeds, motherboards use divider that create a ratio of [FSB CPU] [memory frequency] or through the use of percentages of the FSB. However, intrinsically, it is possible to see the problem with this and why synchronous operation is preferable on all PC platforms. For if there is divider, then there is going to be a gap between the time that data is available for the memory, and when the memory is available to accept the data (or vice versa). There will also be a mismatch between the amount of data the CPU can send to the memory and how much the memory can accept from the CPU. This will cause slow downs as you will be limited by the slowest component.

200MHz FSB speed with 120% or 5:6 (FSB: Memory ratio) results in 240MHz memory speed (DDR480)

This example shows the memory running at higher speeds asynchronous. Assume we have a Barton 2500 + which by default is running at a FSB of 333 MHz (166 MHz X 2) and we also have PC3200 memory which by default is running at 400 MHz. This is a typical scenario because many people think that faster memory running at 400 MHz, will speed up their system. Or they fail to disable the SPD or Auto setting in their bios. There is NO benefit at all derived from running your memory at a higher frequency (MHz) than your FSB on Athlon XP / Duron system. In actuality, doing so has a negative effect. Why does this happen? It happens because the memory and FSB can not "talk" to each other at the same speeds, even though the memory is running at higher speeds than the FSB. The memory would have to "wait for the FSB to catch up, because higher async speeds forces de-synchronization of the memory and FSB frequencies and therefore increases the initial access latency on the memory path, causing as much as a 5% degradation in performance.

That is another Ramifications of the limiting effect of the AMD dual-pumped FSB. A P4's quad pumped FSB (along with the superior optimization of the async modes) allows P4's to benefit in some cases from async modes that run the memory faster than the FSB. This is especially true of single channel P4 systems like the older i845 series where running an async mode that runs the memory faster than the FSB was crucial to top system performance. There still are synchronization losses inherent in an async mode on any system, but the proper FSB bandwidth of the P4 allows the additional memory bandwidth produced by async operation to overcome these losses and produce a net gain.

So it is less useful for your RAM clocks higher than your FSB can, because the RAM must wait until the FSB back to level. This money (apparently) stronger for AMD systems than Intel's, but it is in both cases up.

There are also voltages indicated by Intel up as long as you do not exceed these values (and the cores are not too hot of course) you're fine. If you are not happy with the extra volts that your FSB or Core go, you can try to reduce it naturally! this would be the last step of the clock should be on, if you have found a stable setting

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