FSB? L2 cache? How much do I want and what does it do?

[VirusType2]

ok, thanks to everyone who helped me select the parts I need to build my new PC!

I have a question that came up while shopping..

The AMD 3200+ Processor comes with a 512KB L2 cache

I saw a P4 proc that has a 1 megabyte L2 cache and 800 Mhz FSB.

My questions are:
What is an FSB?

What is a 800 Mhz FSB, and why doesnt the AMD proc tell me what its FSB amount is

Secondly

do all AMD 3200+ come with 512KB?
Do some come with more?

How much do I want and what does it do?

 

[NetGuru42]

FSB is short for "Front Side Bus" and it's the speed of the connection between the processor and the main high-speed components (such as RAM and AGP, etc.) Basically FSB is a big part in how fast your computer will run. The differences are huge between Intel and AMD. AMD has something called HyperTransport on their 64-bit processors which allows the FSB to be CONSIDERABLY faster than the Intel processors 800Mhz, although you may see that it's rated at a slower speed, or not rated at all, as you said.

L2 Cache (512K in AMD's case, 1MB in Intel's) is basically tripped-up RAM in your CPU. It's there to provide a place that the CPU can store it's instructions and stuff for fast access. It used to be that the more cache, the faster the CPU... however, not so much anymore. Once you get past 512K, the performance isn't effected much. In this case, the AMD 3200+ will substantially outperform the Intel P4, even though it has 1/2 the L2 Cache size.

Good luck. :cheers:

 

[Asus]

Cache is just a temporary place to store data that the CPU is working on. In general, more is better but you don't get to choose.

A pentium 4 and Athlon 64 have different ways of using L1 and L2 cache. Also size isn't the most important factor but latency (how long it takes before it's ready). Intel's P4 saves a copy of it's L1 in the L2 cache. AMD does not do that.

Athlon 64's don't have a FSB exactly. It's a different design. Though you could say it's 800 or 1000 (depending on the system). Just more efficent than the standard FSB design.

In short, the standard design sends data one way (up or down) while the AMD"s HT design can send data both directions at the same time. Not to mention Intel's FSB still has to handle the Memory traffic (which is a lot). AMD has their memory controller right on the CPU so their design doesn't have that memory traffic to cause any slow down.

 

[NetGuru42]

Asus man, you a board manufacturer or something? jeez. :cheese:

actually, no... I'm just trying to spare everyone from the technobabble.

 

[Asus]

actually, no... I'm just trying to spare everyone from the technobabble.

haha yeah

 

[VirusType2]

So the AMD 64 3500+ 939 for $274 will be my choice..
this does or doesn't have HT?

I thought HT was a Pentium 4 thing

EDIT: One last thing (I hope)
How much better performance in games can I expect from what I currently use:

Intel Celeron D 2.666 GHz

To what I will buy:

AMD 64 3500+ 939

or

AMD 64 3200+ 939

thanks!

 

[Quixoticism]

Hyper Threading IS an Intel thing.

Now, bear this in mind that I do not have an AMD 64, but you should get a very large performance boost in games(as long as you're not GPU bound) going up to any Athlon 64 from a Celeron. Celerons are like mainstream video cards, they run well enough to run, but are no match for the higher end tech.

 

[VirusType2]

Im sorry, what do you mean "as long as Im not GPU bound"?

 

[Quixoticism]

GPU is you Graphics Processing Unit, AKA video card. And being GPU bound means that your card is holding the rest of your computer back in performance, mostly in games.
As long as you have a decent video card your computer will scream.

I used to have a 766 Celeron(now dead) with a GeForce 2MX400 64MB and it would choke in Warcraft III at minimalistic settings. UT2003 was a joke. But when I upgraded to my current Athlon XP2000+ my performance skyrocketed and I could run WC3 in a great resolution at much better frame rates than before with the same video card, but it still held me back.
I don't how large a performance boost you will get with your CPU upgrade, but you will most definately notice it and be very pleased like I was with mine.

 

[Asus]

HT means different things for AMD then intel which can be confusing.

When you see HT refering to AMD it means HyperTransport, that thing we talked about above being different than the standard FSB.

 

[NetGuru42]

HT means different things for AMD then intel which can be confusing.

When you see HT refering to AMD it means HyperTransport, that thing we talked about above being different than the standard FSB.

Whereas HT in Intel language means HyperThreading. It's basically a virtual dual-proessor system. In other words, it tries to make your computer act like it has two processors rather than the 1 physical one that's really in it. There some minimal performance gains from this.

 

[furiousV]

usually, for HyperThreading, its abbreviated HTT, for Hyper Threading Technology.
some games actually have options to make use of it, and some video encoder programs also can take advantage of it.

could someone please explain the difference between FSB and External Clock, mines at 800FSB and my external frequency is 200MHz. multiplier 14 im confused.

 

[Asus]

The clock is what the PC gets all of it's frequencies from. 200MHz determines the CPU speed with a mulitplyer. It determines memory speed, AGP and PCI bus speeds with ratios. Also, the FSB actually runs at 200MHz but it's RATED at 800 since it's a quad pumped bus (for the P4). Not the same as the CPU's multiplyer since the CPU actually runs at it's 3.2GHz speed or whichever model it is.

 

[furiousV]

some more stupid questions to add:
what does Quad pumped mean, or is that like DDR, which runs at 200MHz but since it works twice the rate they just acll it 400
and why quadpump the FSB, what good does it do?
thanks for bearing with me

 

[bosox188]

You're going to see a huge performance difference in CPU intensive games going from a Celeron to Athlon 64. And make sure you get the 90nm 3500+ (Winchester core) it's much cooler and if you wanted to overclock one day it would be awesome for it.

 

[DrDevin]

You are right about quad pumped. A CPU might have an external clock of 200 but it is multiplied by 4 (quad pumped) to 800 and then multiplied by the CPU multiplier to get the actual rating in Mhz or Ghz. The "effective" clock is achieved by sending data more than once per cycle. The signal that sends data isn't a sinusoidal wave, but is comprised of squares. This creates a plateau at the top and bottom of each wavelength. Data can be sent at the top and bottom, so now you are sending 2x the data at the same true clock, effectively 400MHz now. Intel has a way of "Quad-Pumping" their bus (to use their lingo), which doubles it again, giving you an 800MHz bus. AMD does things a little different with the HyperTransport bus however. For your CPU comparison.

"But the K8 based Sempron 3100+ does some serious damage, outperforming the Celeron D 335 by an incredible 53%. For a budget Doom 3 system, you will want to steer far away from a Celeron D and towards the Sempron. As we've seen before, the cache size dependency of Doom 3 on the Pentium 4 is significant and even though the Celeron D and the Sempron both only have a 256KB L2 cache, the Sempron's on-die memory controller helps reduce the impact of such a small cache on Doom 3 performance.

The winner here is Sempron."

That is an a sample of the celeron vs a sempron in doom 3. As for your Athlon 64 3500+ and 3200+:

Celeron D 335: 49.3

3500+: 94.7

3200+: 85.3

This is purly doom 3 framerate tests. In encoding we see another large difference along with any other tasks you wish to accomplish (that rely on the CPU of course!).

You can find the tests and more info at http://www.anandtech.com and http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2149 for the article I took the performance numbers out of.