FSB:800MHz, mobo supports 800MHz, DDR400MHz Ram; Bus speed = 200Mhz??? - Techist - Tech Forum

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Old 03-25-2006, 06:57 PM   #1 (permalink)
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Question FSB:800MHz, mobo supports 800MHz, DDR400MHz Ram; Bus speed = 200Mhz???

Why is my bus speed not 400MHz?
- CPU = Athlon XP 64 (Sempron) [socket-754] 2.0GHz
- - FSB=800MHz

- Mobo = MSI K8T Neo-V
- - Supports 800MHz

- Ram = 512MB DDR400 Crucial link


I thought the bus speed is limited by the lowest performing component, which would be the memory; which is at 400MHz. Am I not correct?





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Old 03-25-2006, 07:59 PM   #2 (permalink)
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Everything appears to be right.... Your HTT in reality is only supposed to be 200 at stock. Your RAM will run at the 400Mhz like its supposed to if your still stock. The only reason it appears to run at 200Mhz is because it's DDR ram, which stands for Double Data Rate, or something similar.
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Old 03-25-2006, 10:26 PM   #3 (permalink)
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The FSB is Quad pumped ( 200 x 4 = 800)

You also have your ram running at single channel which is 200mhtz. Buy another stick of the same ram and size for DDR400.
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Old 03-25-2006, 11:40 PM   #4 (permalink)
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Quote:
You also have your ram running at single channel which is 200mhtz. Buy another stick of the same ram and size for DDR400.
wrong. the ram says its at 200mhz because it is at 200mhz. the reason they say DDR400 is because it is Double Data Rate. that is, it runs at 200mhz but can read/write twice per clock cycle effectively giving it a frequency of 400mhz. the FSB is actually 200mhz but says 800mhz because it is "quad-pumped" like turtile said.
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Old 03-26-2006, 12:22 AM   #5 (permalink)
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Whats wrong?

I'm saying that you need two sticks to run DDR which is 200 x 2 which is 400. Both sticks run at the same time giving twice the speed.

Its running at 200 with only 1 stick.
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Old 03-26-2006, 12:27 AM   #6 (permalink)
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that is wrong. you are confusing DDR with dual channel. DDR has nothing to do with how many sticks of ram you have. dual channel is having 2 sticks (in some cases 4) running on seperate memory channels giving a 128 bit wide bus rather than 64 bit. DDR400 will run at 200mhz no matter what because that is its actual frequency
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Old 03-27-2006, 12:02 AM   #7 (permalink)
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OK, I really didn't understand you guys' explanations. So I guess my next question is this: in order to run at 800mhz (the max FSB of the CPU), what do I have to do?

My previous computer's bus speed was 166mhz when it could've gone up to 400mhz. I'm still having the same problem of not running at max potential.
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Old 03-27-2006, 01:38 AM   #8 (permalink)
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there is nothing wrong with your setup. its just you are confused about the way the modern BUSes work. the 800mhz bus you are thinking of would be the LDT bus which is probably running full speed (quad-pumped), the actual FSB is 200mhz and the ram is at DDR400 which is actually 200mhz as well
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Old 03-27-2006, 09:09 AM   #9 (permalink)
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Quote:
Originally posted by turtile
Whats wrong?

I'm saying that you need two sticks to run DDR which is 200 x 2 which is 400. Both sticks run at the same time giving twice the speed.

Its running at 200 with only 1 stick.

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Old 03-27-2006, 10:00 AM   #10 (permalink)
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Quote:
Originally posted by turtile
You also have your ram running at single channel which is 200mhtz.

Socket 754's can't even run in dual channel
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