core2duo and dual channel memory efficiency

[mrhuggles]

i am running dual channel 800mhz, and im getting just slightly over 50% efficiency, unfortunately there is no way i can run a half ratio, my board will only run 1:1 and above [i think they are all like that?] wondering if there is anything i can do to maybe get a little better efficiency from dual channel in the core2 generation

 

[JC316]

Well, I can tell you that all boards run 1:1 and above. Otherwise, I am not sure.

 

[_jM]

This is totally off topic, I was reading your system specs to the left and it says your CPU is @ 4 volts.. thats supposed to say 1.4v correct.. cause there is absolutely no way in hell that E2140 can runn 4v....

 

[mrhuggles]

oops, it was at 1.4v lol i changed it back to 2.4ghz tho, i really didnt need the extra clocks for gaming.

and also i really like having almost no temps

 

[EnglishLion]

Your E2140 has an 800MHz bus so the DRAM on a 1:1 ratio will run at 800MHz maximum unless you overclock the bus.

I have a E2160 also on an 800MHz bus, mine is with 2GB of DDR3 1066MHz which at stock fsb speed runs at 800MHz. You have the choice of sticking with 800MHz and tightening the timings to get more out of your memory or overclocking your CPU to raise the bus which should in turn raise the memory speed.

My E2160 is running at 3.3GHz on a 367MHz bus speed which pushes my DRAM up to 1468MHz on slightly relaxed timings.

There are some exceptions to this where the motherboard chipset runs with a fixed memory clock. My Abit F-i90HD has completely fixed memory clocks, you set 800MHz for example and that's what you get. No way to overclock the memory at all

 

[mrhuggles]

that shouldnt effect dual channel efficiency? if anything having a non 1:1 or less ratio should lower dual channel efficiency i would think...
on the nforce2 you could have the FSB twice as fast as the memory, and then with all the extra bandwidth across the fsb you could have more than 50%...

ie: im only getting like +5% bandwidth for being dual channel is that normal and is there any way around it? in the core2 generation i mean, cant very well drop below 1:1

EDIT: after alot of reading, and testing it looks like core2's memory bandwidth bottleneck is more FSB than anything else, guess i was right in going with 400mhz fsb then

soon as i get a memory cooler i intend on pushing it alot further. as it is i only run the memory at 1.8v for that reason i guess thats the best way to get memory bandwidth out of the core2 generation....

EDIT2: thats somethign i wish someone would explain to me, why a QDR bus cant keep up with dual channel DDR it seems to me that it should be a perfect match :?

 

[EnglishLion]

Sorry, must have misunderstood what you were asking - thought that you were wondering why your 1066MHz memory was running at 800MHz.

How are you measuring 'dual channel efficiency'? Running benchmarks of 2 x 1GB versus 1 x 2GB or something?

 

[mrhuggles]

i am simply running sandra memory bandwidth benchmark, my dimms should do around 6400mb/sec max theorhetical each and together in dual channel they only do slightly above that

 

[sneekypeet]

so try to run a 1:1 divider and a 400FSB with a 6X multi if you dont want to OC. Check back in sandra and see if raising the bus will help out with the efficiency!

 

[deathvirus_me]

Your E2140 has an 800MHz bus so the DRAM on a 1:1 ratio will run at 800MHz maximum unless you overclock the bus.

Actually for the E2140, running at stock FSB and ddr2-800, the ratio will be FSB : DRAM will 1:2 and not 1:1 .. proccy FSB will be at 200(*4), and RAM at 400(*2) .. 1:1 signifies both being at same clock

From my experiences, i can say that the C2D's are very much FSB sensitive, meaning it is preferred to run at higher fsb with lower multi than stock settings to obtain the best mem. performance without drastic changes on the CPU ...

 

[EnglishLion]

Actually for the E2140, running at stock FSB and ddr2-800, the ratio will be FSB : DRAM will 1:2 and not 1:1 .. proccy FSB will be at 200(*4), and RAM at 400(*2) .. 1:1 signifies both being at same clock

From my experiences, i can say that the C2D's are very much FSB sensitive, meaning it is preferred to run at higher fsb with lower multi than stock settings to obtain the best mem. performance without drastic changes on the CPU ...

Yes 1:2, your right - I sit corrected.

C2D being fsb sensitive, I guess makes sense being as the memory controller is in the northbridge rather than on the CPU die like with the AMD processors.

 

[mrhuggles]

i already run 400mhz fsb, 1:1 ratio [800mhz]

EDIT: yeah see, with a 1:1 ratio, it seems that somehow 800mhz ddr maxes out a QDR bus [even tho memory is half QDR clock, DDR]
i always tought the core2duo would be ok with dual channel because its bus is QDR and i thought that would be enough for dual channel DDR but its not... so i guess its exactly like the barton, you have to double your FSB and half your memory ratio to get full[mostly] effect of dualchannel, but on the p35 you cant go below 1:1 hmmmmmmmmmm question, can you go below 1:1 on the later chipsets like the X48?

 

[EnglishLion]

I doubt the X48/p45 has anything different than the X38 and P35 with regard to memory ratios. I ran Everest Memory Read Benchmark last night on my system and got 9700Mb/s - that's with a 367fsb and 1468MHz.