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Discussion Starter · #1 ·
What speed RAM should i recommend to someone with an AMD board. I know with Intel if the bus speed is 400 they dont need pc3200 just 2700 and thats actually running faster anyway,right. So how does it go with AMD boards, are they quad pumped or what? I heard something about them just being divided by 2 to get the right speed instead of 4 like intel.

Help me out fellas.
Thanks.
 

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Quote:

Originally Posted by Industrial
What speed RAM should i recommend to someone with an AMD board. I know with Intel if the bus speed is 400 they dont need pc3200 just 2700 and thats actually running faster anyway,right. So how does it go with AMD boards, are they quad pumped or what? I heard something about them just being divided by 2 to get the right speed instead of 4 like intel.

Help me out fellas.
Thanks.

AFAIK thats correct, they are doubled just like DDR. If you get a 200mhz FSB CPU (which would be 400Mhz) then get pc3200 which has a 200Mhz bus (200x2=400).
 

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I'm not 100% sure on intel's, but I think all of them are quad pumped.

So:

an 800MHz bus INTEL processor requires = 800/4 = 200...200 = PC3200
a 533MHz bus INTEL processor requires = 533/4 = 133...133 = PC2100
a 400MHz bus INTEL processor requires = 400/4 = 100...100 = PC100 (not sure on that)

AMD's are not quad pumped, so:

A 400MHz bus AMD processor requires = 400/2 = 200 = PC3200
A 333MHz bus AMD processor requires = 333/2 = 166 = PC2700
A 266 MHz bus AMD processor requires = 266/2 = 133 = PC2100

I hope that helps in some way.
 

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Discussion Starter · #4 ·
What about AMD FSB's that say 1200mhz. If you split that you get 600. There isnt even memory out that can do that 1:1. So what do you do in that case? or am i missing something?

Doesnt pc100/133 have a differant socket?
 

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Quote:

Originally Posted by Industrial
What about AMD FSB's that say 1200mhz. If you split that you get 600. There isnt even memory out that can do that 1:1. So what do you do in that case? or am i missing something?

Doesnt pc100/133 have a differant socket?
I am not familiar with a lot of AMD CPU's, but where did you see a AMD with 1200Mhz FSB?? I thought the highest they had was 400Mhz.
 

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amd 64 have 1200-1600mhz buses.....thats the hyper transport, then xp's only go to 400 mhz. so in a way, the 64's are quad pumped....400x4 or 300x4 depending on the model
 

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Discussion Starter · #7 ·
so if you have 400mhz x 4 for an AMD 64 then your still limiting it becasue of ram using pc 3200 or even 4000. Right?
 

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.....hmmmm...wait no...somehow this is not right...i think i got that wrong...somehow it ends up with 200 witha 1200-1600 bus. sooo....yeah...and i know its more then x2. ill check and post later
 

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The Hyper Transport bus on AMD's dosent work like the FSB does. The AMD64 4000+ has a 400MHz FSB 400/2 = 200MHz ram PC3200. The AMD64 4000+ also uses an 1GHz HT bus. You need to buy your ram to work with the FSB not the HT bus. AMD does not currently make a processor that needs more than DDR400 ram PC3200.

You may have seen the 1600MHz bus number on a AMD64 that uses a 800MHz HT bus. The HT bus has the same data rate up and down stream so some marketing *&%er may have called it 1600MHz.
 
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Discussion Starter · #10 ·
you dont happen to know how the Hyper Transport works, or how it gets its own mghz rating?
 

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The HT bus on AMD boards replaces the FSB. The CPU, North Bridge, PCIe, ect... are all connected by the HT bus just like the FSB used to connect these things. New AMD's don’t have a FSB; they use the HT bus instead.

The ram on an Intel board is connected to the memory controller (in the North Bridge), which is in tern, connected to the CPU by the FSB.

The ram on a new AMD board is connected directly to the CPU's onchip memory controller and does not use the HT bus.

The speed of the HT bus is determent by the ram clock speed. The AMD 4000+ uses a X5 multiplier to get the 1000MHz HT bus from the 200MHz ram. Also, I was looking around and it is just a marketing thing when they say 2000MHz HT bus, it really operates at 1000MHz. Note: it is not the same as Intel "quad pumped" FSB were 200MHz X 4 = 800MHz. The HT bus operates at 1000Mhz.

Side note: Intel’s 800MHz FSB is half-duplex. (Shares it bandwidth with the up stream and down stream traffic.) i.e. If there is lots of up stream traffic there will be little bandwidth left for down stream traffic. AMD's 1000MHz HT bus is Full-duplex (there is the same amount of bandwidth for both up and down stream traffic and they do not share it.)
 
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Quote:


Originally Posted by BSman

The HT bus on AMD boards replaces the FSB. The CPU, North Bridge, PCIe, ect... are all connected by the HT bus just like the FSB used to connect these things. New AMD's don’t have a FSB; they use the HT bus instead.

The ram on an Intel board is connected to the memory controller (in the North Bridge), which is in tern, connected to the CPU by the FSB.

The ram on a new AMD board is connected directly to the CPU's onchip memory controller and does not use the HT bus.

The speed of the HT bus is determent by the ram clock speed. The AMD 4000+ uses a X5 multiplier to get the 1000MHz HT bus from the 200MHz ram. Also, I was looking around and it is just a marketing thing when they say 2000MHz HT bus, it really operates at 1000MHz. Note: it is not the same as Intel "quad pumped" FSB were 200MHz X 4 = 800MHz. The HT bus operates at 1000Mhz.

Side note: Intel’s 800MHz FSB is half-duplex. (Shares it bandwidth with the up stream and down stream traffic.) i.e. If there is lots of up stream traffic there will be little bandwidth left for down stream traffic. AMD's 1000MHz HT bus is Full-duplex (there is the same amount of bandwidth for both up and down stream traffic and they do not share it.)

Interesting, now I want to learn more about this... Time to hit google.
 
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