FSB and speeds

[Arnagath]

I dont know if their is some kind of formula that can be used to count the speed change compared to the FSB.

What I really was wondering is which is faster (if they both have the same RAM):
P4 1.7 with 400 FSB
Athlon XP/Duron 1.9 with 333 FSB

 

[xeenrecoil]

heya Arnagath;

PC2700 has a higher maximum throughput then PC1600, the Athlon would out perform the P4 in this case, because it has a 333x2 FSB, where as the P4 has a 100x4 FSB reguardless if the P4 had pc2700 or not, the FSB couldnt be overclocked enough to make up the difference in memory throughput.

***Important Note***
I thought you were refering to the 333x2 - 666FSB version of the athlon.<P ID="edit"><FONT SIZE=-1><EM>Edited by XeenRecoil on 09/07/04 01:01 PM.</EM></FONT></P>

 

[jammydodger]

WTF are you talking about d00d? The P4 has a quad pumped 100Mhz bus resulting in a 400Mhz bus, whereas the Athlon XP has a 166Mhz fsb that sends two signals every clock cycle resulting in a 333Mhz FSB.

The important thing here is not the FSB though, P4's are very bandwidth dependant and so love high FSB's and lots of memory bandwidth. The Athlon XP however is not so bandwidth dependant which is why AMD did not bother raising the FSB above 400Mhz with their XP line...the performance gains simply wernt worth the extra effort.

In this case the Athlon XP is definatly the faster CPU for the majority of applications.

 

[Arnagath]

alright so then the Athlon is definatly better then. That is good to hear.

Thanks allot for your help

 

[xeenrecoil]

i thought he was refering to the 666FSB Athlons, simple mistake...athough this is semantics, AMD introduced the term "pumped" the althon was double pumped, the intel had a quad pipeline.

Also in any case the Althlon is only better for gaming for the most part, in most other areas it gets its butt kicked, although as of late the althlon has caught up somewhat in the areas it was previously lacking.

 

[jammydodger]

There is no such thing as a 666Mhz fsb athlon XP, 400Mhz is the highest FSB supported by the XP line.

Intel generally rules in the video editing segment and synthetic benchmarks. But since we are talking about a P4a the lead is not very great. The 400Mhz FSB really bottlenecks this CPU, and if we are talking about a P4a willamete core with only 256kb of L2 cache then I think that the athlon XP would win in everything.

 

[xeenrecoil]

Jammydodger;

AMD XP was recently 333x2 = 666FSB its "double pumped"
the current one barton is 400x2 = 800Mhz FSB
AMD refers to the actual Mhz of the DDR, which in this case is pc2700 333Mhz unlike intel. therefore it can be confusing to someone who doesnt know better.

the P4c is 200x4 = 800FSB.

i think you better check your specs man. Its marketing terminology but reguardless its still rellevant.

 

[jammydodger]

lol, d00d the athon XP barton core uses 200Mhz FSB! I is a DDR bus which means it transfers data on the rising and falling edge of every clock cycle. This means that you get a peak theoretical bandwidth of 8(the bus is 64bits wide)*200 (200Mhz bus)*2 (because its double data rate) = 3200 MB/s which just so happens to be exactly the same as PC3200 RAM...which is also reffered to as DDR400.

The fact that is is reffered to as DDR400 does not mean 2*400 it is actually a marketting term that was used in order to show the customer that DDR was faster than SDRAM.
If you here PC133 or DDR133 you think they are the same speed...but if you here PC133 and DDR266 then you think wow DDR266 is faster.

 

[xeenrecoil]

jammy;

i can see this is going to go all day.

pc3200 - 200Mhz x2 = 400Mhz
the Athlon is double pumped which makes it 400x2, its actualy a 800Mhz FSB.
They only call it a 400FSB because it is smart marketing, it doesnt confuse the consumer.

 

[jammydodger]

Ok im going to need some help here? Anyone?

The pentium4 has a quad pumped 200Mhz (the pentium 4c and e that is), in order for the memory to keep up with this FSB they have introduced Dual channel RAM. This is when two 64bit memory busses are combined into a 128bit memory bus, so when 2 or 4 indentical sticks of PC3200 are combined you get a maximum bandwidth of 6,400 MB/s. This is perfect for the P4 since 800*8 = 6,400 MB/s.

Now the Athlon XP can also use dual channel, but since the Althlon XP has a maximum FSB of 400Mhz there is no point in having 6'400 MB/s of bandwidth...so instead dual channel mode on Athlon XP's does not double the bandwidth but instead staggers the latencies.

 

[Obtuse]

Listen to jammy; he's right. The Front side bus is 200mhz. The XP is "double pumped" to run at 400mhz. The DDR ram is not "double pumped". It runs at 200 mhz, it transmits on the rising and falling edge of the cycle. So it transmits twice each cycle to keep in sync with the Proc which is "double pumped" to go twice as fast.

Proc = 200 X 2; Ram = 200(rising and falling edge)

The ram and the processor each manage to go twice as fast as the FSB, they just go about it different ways.

"It's too late now anyway. That song is stuck in my head and the only way to get rid of it is to blow it out. With a bullet!! - Carl

 

[jammydodger]

Thank you

 

[jammydodger]

Man i love being right, it makes me feel all warm and fuzzy inside.

 

[Mr5oh]

Just a another vote for Jammy, Xeen what were you smoking?

Parent Poster, Listen to Jammy.

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[xeenrecoil]

dunno thats a good question, but what ever it is i want more of it woooohoooo!

/action eats some crow

Sometimes i just get something in my head and no one can convince me otherwise till i go look for myself, which btw i did, and i was wrong all along, im not sure why i was thinking that, oh well im a big enough man to admit when im wrong, no big deal, i guess a human cant be infallible, no matter how hard he tries heh.

 

[Mr5oh]

Xeen, you had me wondering there for a moment, I know you are knowledgable, just a minor brain lapse I guess.

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[jammydodger]

Sometimes i just get something in my head and no one can convince me otherwise till i go look for myself

Dont worry about it, Im exactly the same...in fact i think most of the people in this forumn are. Well at least u learned summik and thats what this forumn is about.

 

[ChipDeath]

dunno thats a good question, but what ever it is i want more of it woooohoooo!

I'll have some too, if you've any spare... - you could use a 800FSB Athlon to light it I'd imagine...

---
Epox 8RDA+ V1.1 w/ Custom NB HS
XP1700+ @200x10 (~2Ghz), 1.4 Vcore
2x256Mb Corsair PC3200LL/1x512Mb Corsair XMS PC4000 2.5-3-3-7
Sapphire 9800Pro (VGA Silencer Rev3) @418/742

 

[Crashman]

Wow, and I thought the whole time you were just trying to confuse him!

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