2gb ?'s

[Mr.Suave]

i decided to go with 2gb RAM but im not sure wether to go with 4x512mb @ CAS2 2-2-2-5 or 2x1024mb @ CAS2 2-3-2-5 both DDR400 (PC 3200).
will the AMD x2 4200 be able to use all 4 of the DIMMs at max speed?? becuase i read in RAM 101 that if 4 are used it will drop the speed from PC3200 to PC2700. Also confused about where is said an Athlon 64 "venice/san deigo" core would be able to use full speed but then says with the exception of Athlon64-based processors

With respect to the Athlon64 with on-die memory controlers, those running with "Venice/SanDiego" cores (or newer) will be able to run with all DIMM slots populated at the full speed. With the exception of Athlon64-based processors (i.e., on-die memory controllers), this isnt a concrete rule in that some memory controllers will only drop the speed depending on the type of DDR (and i would imagine DDR2) memory installed (i.e., double sided or single sided).

Generally double-sided (DS) memory is a bit more finicky than single-sided (SS) meaning DS memory will tend to downclock (i.e., 4 sticks of PC3200 will run at PC2700). How do servers, which require craploads of memory ... deal with this? They [generally] use something called Registered Memory which, to simply state, improves signal stability (thus allowing the memory to run at the higher clock)

is the ram i chose SS or DS? how can you tell?

 

[Hairy_Lee]

first thing, im not sure what your processor is capable with regards to how many sticks it can access without dropping the memory speed; however my past experience is that they do drop the speed down when all the slots are populated.

double-sided ram - ram chips on both sides
single-sided ram - ram chips on one side

personally i would go with the two larger modules so that there is room for upgrade should you need it. the single change noted in the timings is not very significant at all and i would say i would only be noticable in memory benchmarks

 

[Geoff]

With my motherboard it only drops the speed if you have 4x double sided memory sticks. I would go with the 2x 1GB.

 

[Mr.Suave]

ok thx guys ill go with the 2x1gb and thx hairy for clearing up wat SS and DS ment
and i think, i get the whole thing about the athlon64.

 

[34erd]

Socket 939 is capable of running all DIMMs populated at DDR400, however it will be forced to run 2T comand rate, which is a big performance drop on the K8 architechture. So I would go with 2 x 1 gigabyte for upgradability and the 1T comand rate

Also CAS is the most performance afecting timing so since they are both 2 the performance difference will be small.