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memory brandwidh issue

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makaka

Member
Joined
Jan 5, 2004
Location
home
hi
i was looking for the memory controler those due about his efficasity
in amd s754 case the efficasity is alwais 95-98 range so u will get rawlly the max memory brandwidh
running @ 200 default A64 3000+ i was getting 98% of effcasity=3136
with timing 7-3-3-2.5t
running @ 270 A64 3000+(2430) i was also getting 98% of effcasity with 1:1 ratio =4215 with timing 7-3-3-2.5t
in the amd 939 case is a bit deferant with a lot lower efficasity using the dual channel
@ 2700 300*9 and memory(2*512) @ 166 (250mhz) 7-3-3-2.5t
in theorie with 100% efficasity i must get 8000mb/s but i am only getting 90-89% range about 7000-7100 mb/s
@2970 330*9 and [email protected]~248 7-3-3-2.5t i am getting the same about 90-89 range

so the cpu speed is not issue ,is not holding the memory brandwidh back
as i know no nothbridge in those nforce3,4 mobo and the memory controler is inside the cpu so the mobo is not issue here

can anyone explain to me why there is no 98-95% range efficasity.
is it the duall channel eating from the cpu efficasity of brandwidh or what exactly
thanks
 

The Coolest

Senior Member
Joined
Jul 29, 2001
Its spelled "Efficiency", just so you know :)
And yes, in fact the s754 memory controller is more efficient than the s939 mem controller. I don't know why, but it is a fact, I guess its all because of the time it takes to synchronise both channels, and to wait till the next read is needed.
 
OP
makaka

makaka

Member
Joined
Jan 5, 2004
Location
home
"Efficiency" thanks for input my english is so crappy and i must leave with it :)
-the idea of "the time it takes to synchronise both channels" is really rock.
thanks for replay
 

goog`

Member
Joined
Jun 18, 2005
Location
mecca
dual channel has never been truly double bandwith it's just better than single; thats the great thing about a theory. It be interesting though to see if in single channel the 939 offers the same bandwith as the 754.