1600Mhz faster than 2000Mhz?

325cic · Mar 22, 2010

okay, I am confused.

I overclocked my cpu to 4420 (210x21). if I run my ram 2:10 - 2100Mhz 9-10-9-T1, it bench much slower bandwidth compare to run at 2:8 - 1680Mhz 7-8-7-T1. I thought higher ram frequency will have bigger bandwidth. In this case, it's almost cut bandwidth in half.

so, why need higher than 2000Mhz rams?

Automata · Mar 22, 2010

You have three variables changing, the RAM speed, the timing and the divider. It shouldn't be half the bandwidth, but the latter setting you posted (1680 7-8-7) should have more bandwidth. Some motherboards also have a "problem" running a certain divider. Some dividers may be faster than others and you really just need to play around with them to get a feeling for what your system is capable of.

If nothing changes (timing) and you increase the bandwidth, it should be gaining bandwidth linearly.

Brutal-Force · Mar 22, 2010

^^^ What he said.

325cic · Mar 22, 2010

thideras said:
You have three variables changing, the RAM speed, the timing and the divider. It shouldn't be half the bandwidth, but the latter setting you posted (1680 7-8-7) should have more bandwidth. Some motherboards also have a "problem" running a certain divider. Some dividers may be faster than others and you really just need to play around with them to get a feeling for what your system is capable of.

If nothing changes (timing) and you increase the bandwidth, it should be gaining bandwidth linearly.

If I run 2:10 2100Mhz rams at 7-10-9-T1. bandwidth will reduce even lower. So, It's not relate to memory timing. it has to be some other timing change when divider is higher cause overall bandwidth drop.

oh well, I changed back to 2:8 1684Mhz 7-8-7-T1 with 1.5V. I play with it more if we have memset that work for MSI x58 :santa:

ch0b1ts · Mar 22, 2010

You can think of the speed of the RAM as a measure potential maximum bandwidth. The tighter the memory timings, the closer you come to the max bandwidth. The more loose the timings become, the less bandwidth you have.

So, I could envision a situation where your timings are so loose that you actually have less bandwidth than if you ran the memory at a slower speed with very tight timings.

325cic · Mar 22, 2010

I got it!!!!! damn, only one setting change affect that much bandwidth.

change B2B Cas# to 0 ( disable), it will boost for bandwidth to maximum. I was set to 13 (auto default for divider 5x).

1600Mhz faster than 2000Mhz?

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