Memory question, dual channel 333mhz vs single channel 400mh

specr1

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Feb 8, 2006
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Hi all
i have a little problem on my hands
my computer

AMD 4400+ X2
Sapphire X800XL
4 x 512 Kingston ram, CAS 3
Asus A8N-E Motherboard

well my problem is that i can run the ram 2 different ways

2gigs single channel 400mhz @ CAS 3
2gigs dual channel 333mhz @ CAS 2.5

i have asked alot of ppl from my local computer stores and i get mixed opinions

like, the dual channel will make up for the frequency loss or the dual channel will not make up for th efrequency loss

so i thought i would ask here too

thanks in advance !! :D
 

mpjesse

Splendid
uhhhh no. the dual channel will not make up for the loss in frequency.

I would be more concerned with the fact that the memory won't run at DDR400 in dual channel. There's obviously an issue with the motherboard.

Have you tried looking for a BIOS update? Or replacing it?

-mpjesse
 

specr1

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ok i downloaded it but im quite confused
what exactly am i looking for?
the benchmark numbers are already pre-made from other computer specs

edit: k i found out how to benchmark it

the 3 numbres im looking for are
memory read
memory write
memory latency

am i correct?
 

specr1

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ok i ran the benchmarks and these are the numbers i got

Single Channel Dual Channel
Memory Read 2960 MB/s 4329 MB/s
Memory Write 1010 MB/s 1431 MB/s
Memory Latency 69.7 ns 73.0 ns

so i guess the memory read/write is better but the latency is slower
so which one ? :D
 

WBSpring

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2gigs single channel 400mhz @ CAS 3
2gigs dual channel 333mhz @ CAS 2.5

Let's do some math to get the theoreticals...

To start, are you better or worse when switching between 400 MHz CL3 or 333 MHz CL2.5?[*:28a3987f23] Answer: NO
[*:28a3987f23] Reason:
[*:28a3987f23] 400 MHz DDR = 200 MHz core; 1 / 200 MHz = 5 ns / cycle; 3 cycles * 5 ns / cycle = 15 ns.
[*:28a3987f23] 333 MHz DDR = 166 MHz core; 1 / 166 MHz = 6 ns / cycle; 2.5 cycles * 6 ns / cycle = 15 ns.
Now, what bandwidth should you expect between the different configurations?[*:28a3987f23] Single Channel (400 MHz DDR)
[*:28a3987f23] 400 million transfers / second * 8 bytes / transfer per channel * 1 channel = 3.2 GB/s
[*:28a3987f23] This is why DDR-400 memory is referred to as PC3200.[*:28a3987f23] Dual Channel (333 MHz DDR)
[*:28a3987f23] 333 million transfers / second * 8 bytes / transfer per channel * 2 channels = 5.333 GB/s
So, theoretically, the better solution is the dual channel one, even though you are running at a lower frequency. The benchmarks tell the truth.
Single Channel Dual Channel
Memory Read 2960 MB/s 4329 MB/s
Memory Write 1010 MB/s 1431 MB/s
Memory Latency 69.7 ns 73.0 ns
The latency difference above is negligible and should not be considered a detriment to the dual channel solution. Your system will perform far better in a dual channel configuration.

-Brian
 

parlee

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i swear tom did an artical on somthing like this, the advantages of having dual channel... maybe im dreaming, but one way or another i know ive heard that the difference in performance between dual channel and single channel is minimal so im guessing that dual channel in pc2700 is slower than pc3200 in real world apps... if u play games run the stress test with both configs and see which is better, synthetic benchmarks arnt always the complete truth
 

specr1

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thanks everyone
this question has been bogging my head for a while and i finnaly made a choice and stuck with the 333mhz dual channel

:eek: :eek: