Effect of running memory slower than bus speed on Core i7 X58

[MyLeftNut]

Is there any performance impact in running a divider with memory slower than bus speed? Something like 1250 for memory speed and 1700 for bus speed. With triple channel, isn't there already excessive bandwidth that it would make up for the decrease in memory speed? Or am I misunderstood somewhere? This btw, is regarding an overclocked system at 4.3ghz.

 

[Ben90]

http://en.wikipedia.org/wiki/Computer_bus

What bus may u be referring to?
AFAIK anything related to overclocking shouldn't be running at 1700mhz@4.3ghz so i think ur math is off

I have a gut feeling ur talking about uncore; in which case it needs to run at least 4x faster than your memory mhz. Its not like 775s where things worked really nicely with 1:1 ratios ect; basically just get each component up to its limit and everything works nicely...

 

[MyLeftNut]

Ok, I'll put it in bios template form so it'll be clearer.

CPU Ratio Setting: 20x
BLCK Frequency: 215
DRAM Frequency: ~1730
UCLK Frequency: ~3650
QPI Link Data Rate: ~3870


I get to choose another memory divider where I can get something like

CPU Ratio Setting: 20x
BLCK Frequency: 215
DRAM Frequency: ~1330
UCLK Frequency: ~3650
QPI Link Data Rate: ~3870


Considering that ram timings are the same for both divider choices, would there's still be enough bandwidth with having DRAM Frequency lowered?

 

[RussianSensation]

The difference between DDR1066 vs. DDR2 1866 on Core i7 platform is like 3%. There will be 1% difference between 1730 and 1333, in the majority of applications. Programs that benefit from increased bandwidth such as WinRAR will behave differently though. If your memory is stable at the higher bandwidth, you might as well keep the higher speeds at same timings.

 

[Mr Fox]

Originally posted by: RussianSensation
The difference between DDR1066 vs. DDR2 1866 on Core i7 platform is like 3%. There will be 1% difference between 1730 and 1333, in the majority of applications. Programs that benefit from increased bandwidth such as WinRAR will behave differently though. If your memory is stable at the higher bandwidth, you might as well keep the higher speeds at same timings.

Russian is Correct :

http://forums.anandtech.com/me...=2336278&enterthread=y

 

[IntelUser2000]

According to Intel, dual channel memory is enough for 4 cores. That probably means it takes a 6 core to benefit from triple channel, which is why Gulftown will end up in the X58.

 

[GLeeM]

If your idea is to try running ram lower to get higher CPU - go for it.

 

[MyLeftNut]

Thank you all for your input. I'm trying to find an optimal spot based on my choices. If running lower ram speeds at tighter timings will net me less voltage and stress on motherboard elements while maintaining performance, it would be ideal. I looked into this further and got more exact numbers. I can run my memory at ~1720 9-9-9 @1.65V (haven't tried lower yet), or I can run ~1290 7-7-7 @1.5V. I'm going to try for 6's.