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AMD Athlon Bus Speed Question ^^

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Anonymous
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April 25, 2001 4:48:55 AM

OK..
someone asked me..

if my bus is at 100 or... 200 ( ev6 )

How can pc -133 run at that
doesnt the memory have to be running at the same speed as the bus?

How does that work..
I have pc -133 and someone... told me its useless and i should of for pc -100 becuase the bus is 100MHz..

But i think they run at different speeds correct?

explain pls

-- They have found a way to harness the power of a thunderstorm and expell it with great force!--
April 25, 2001 4:57:52 AM

For someone labeled an "addict" by the forum I'm surprised you don't already know this. Anyway...

If you run a 100MHz bus, you should use PC100 ram. If you run a 133MHz bus, you should use PC133 ram. If you are running PC133 ram on a 100MHz bus it's being underclocked and used as PC100 ram.

If you run a 100MHz bus with DDR (effectively 200MHz) you should use PC1600 ram. If you run a 133MHz bus with DDR (effectively 266MHz) you should use PC2100 ram. If you are running PC2100 ram on a 100MHz bus with DDR, it's being underclocked and used as PC1600 ram.

-Raystonn

-- The center of your digital world --
Anonymous
a b à CPUs
April 25, 2001 5:01:07 AM

I told him that. Damn kid wount listen to me. Hes like "but my memory is 133 so it has to be 266 cause i have double data path way. Im like no it isnt you only have sdram not ddr, but hes thick.

SPUDMUFFIN

<font color=blue>Just some advice from your friendly neighborhood blue man </font color=blue> :smile:
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Anonymous
a b à CPUs
April 25, 2001 5:15:25 AM

I never said my memory was double pumped

i said..
the bus speed is

Then why the hell does my motherboard
Gigabyte 7ZM
support KT133 Chipset and ........
it says supports pc-100 and ....... AND PC 133

and its only for SDram
Why then?
ALSO>>
IN cmos im running a Duron 800 100MHz bus ( 200 EV6 )
and..
in benchmarks
the mem running at 133 is way higher then...
the mem set to 100

why?

-- They have found a way to harness the power of a thunderstorm and expell it with great force!--
April 25, 2001 5:17:28 AM

You can select your frontside bus speed (FSB) in BIOS. If you want to actually use your PC133 memory, set it to 133MHz.

-Raystonn

-- The center of your digital world --
Anonymous
a b à CPUs
April 25, 2001 5:38:38 AM

But his durons a 100 fsb. So there will only be trouble.

SPUDMUFFIN

<font color=blue>Just some advice from your friendly neighborhood blue man </font color=blue> :smile:
April 25, 2001 5:41:02 AM

I don't know a great deal about the Duron, but are you saying AMD locked the frontside-bus speed that the chip will accept? The Duron can't handle a 133MHz frontside-bus? Looks like he wasted his money.

-Raystonn


-- The center of your digital world --
Anonymous
a b à CPUs
April 25, 2001 5:43:07 AM

my cpu is at 100 or ( 200 ev6 )

my memory is set in cmos to..
133

it runs and scores way higher memory benchmarks then with the mem set at 100

how does this work

are u saying if my bus is set at 100, my memory it at pc-100 speeds?

-- They have found a way to harness the power of a thunderstorm and expell it with great force!--
Anonymous
a b à CPUs
April 25, 2001 5:43:36 AM

Ya ya i told him that too. But hey its the cost\performance ratio right? Thats what its all about.

SPUDMUFFIN

<font color=blue>Just some advice from your friendly neighborhood blue man </font color=blue> :smile:
April 25, 2001 5:48:38 AM

"my cpu is at 100 or ( 200 ev6 )

my memory is set in cmos to..
133"

I don't understand what you're talking about here. There is only one bus that's related to the CPU. That's the frontside bus. This is the bus that's used to communicate between the CPU and memory. From where are you getting these 2 differing numbers? If you have SDR (non-DDR) SDRAM, then your frontside bus is running at either 100MHz or 133MHz. Pick one. ;) 

-Raystonn

-- The center of your digital world --
Anonymous
a b à CPUs
April 25, 2001 5:50:53 AM

I know hes crazy. I spent one night argueing over it till i just got mad and logged off ICQ.

SPUDMUFFIN

<font color=blue>Just some advice from your friendly neighborhood blue man </font color=blue> :smile:
Anonymous
a b à CPUs
April 25, 2001 6:27:23 AM

What im saying is
i have NO NO NO NO settings in cmos for the FSB none!

On the board its set to 100...

now.....................
in CMOS i have.. a setting for the memory
100 Cas 2 or.. 133MHz cas 3..
its set at 133MHz with the bus speed at 100

it performs faster in sisoft sandra at 133 then it does at 100
with the bus always at 100...

How is this possible?


-- They have found a way to harness the power of a thunderstorm and expell it with great force!--
Anonymous
a b à CPUs
April 25, 2001 6:29:40 AM

Also
this board handles 133 FSB
but max i can get stable is 118

...


-- They have found a way to harness the power of a thunderstorm and expell it with great force!--
April 25, 2001 6:50:46 AM

"i have NO NO NO NO settings in cmos for the FSB none!"
"its set at 133MHz with the bus speed at 100"

Not only do those two statements conflict, but you conflict yourself in the second statement alone. The FSB is the 'bus speed' that you're discussing. So you obviously have a setting for it. Now as far as the second statement goes, which one is it? 133MHz or 100MHz? It can't be set at both.

-Raystonn

-- The center of your digital world --
Anonymous
a b à CPUs
April 25, 2001 6:55:45 AM

The Via chipsets can run the memory asynchronous to the fsb.

This has existed as far back as the kx133 chipset.

What this means is your fsb will run at 100 (100x2 with Ev6)
and the chipset will run the memory at 100+33 or 133 mhz.

You are not wasting your pc133 on any modern chipset.

The intel people should do a little more research as even the Via chipsets for intel processors can run the memory asynchronus to the bus clock.
April 25, 2001 7:08:21 AM

You're still wasting money. Your processor is not able to use your PC133 memory at a rate any higher than 100MHz.

-Raystonn

-- The center of your digital world --
Anonymous
a b à CPUs
April 25, 2001 7:57:47 AM

I believe what KILRSAT says

i know my memory is running at pc-133 and the bus at
100(100x2)

i know my memory is running at 133


-- They have found a way to harness the power of a thunderstorm and expell it with great force!--
April 25, 2001 8:04:14 AM

Your memory may be running at 133MHz when accessed through DMA by the chipset and expansion cards, but it's being accessed through the frontside bus by the CPU directly; and that is at 100MHz.

-Raystonn

-- The center of your digital world --
Anonymous
a b à CPUs
April 25, 2001 9:17:20 AM

I am running a Duron 700 @ 900 with VIA 133 chipset and the facts do not support your contention.

1. The Duron has a double pumped 100 Mhz bus effectively allowing 2 transfers per clock between the processor and North Bridge.

2. The North bridge "buffers" asynchronous memory transfers between SDRAM and processor.

3. Running asynchronously IS less ideal than running with the same clock (which happens automatically when a 133A chipset is used with a 'C' athlon on 133 SDRAM) but still better than running 133 SDRAM at 100 on a VIA 133.

4. Hint .. also really good idea to set 4 way interleave on the SDRAM for a free performance boost (if your BIOS allows)

If you don't want to accept my word (and I have run the tests) go to Aces where the real experts are!.

I am running an Epox 8KTA-2 mobo (there is not a wide choice in South Africa) and I cannot get processor FSB above 112 (224 double pumped) but this is reported to be a known VIA 133 story (fixed by VIA 133A). My memory (crucial 133 Cas 3)
is then running at 148 Mhz.
April 25, 2001 9:28:47 AM

Man what a confusing thread. Does this guy know what in the world he's saying??
Anonymous
a b à CPUs
April 25, 2001 9:30:16 AM

<b>Raystonn</b>, that is incorrect:
>>>Your memory may be running at 133MHz when accessed through DMA by the chipset and expansion cards, but it's being accessed through the frontside bus by the CPU directly; and that is at 100MHz.<<<<<

The memory bus does NOT spontaneously change its speed. It runs at the same speed, connected to the northbridge, all the time.

<b>tbirdinside</b>, This is how it works:
For both the Athlon, and Duron (all versions) the cpu to northbridge (FSB, ev6 bus) runs at either 100MHz DDR or 133MHz DDR (effectively 200MHz/266MHz). Normally, the memory (northbridge to memory) bus runs synchronously to the FSB, but with the Via SDR chipsets, the memory bus can be clocked at FSB + 33MHz when the FSB is clocked ~100MHz. This is the same for the Via P3 chipset, by the way.

There are some slight downfalls for running the memory asynchrounously to the FSB, but for SDR SDRAM it is possible. This is why the DDR chipsets will ONLY run the memory at 100MHz DDR when the FSB is set to 100MHz DDR (Athlon-B/Duron).

Since the northbridge to cpu bus is runs DDR, the increased bandwidth of the asynchronous memory bus can be utilized, which is not entirely true for the P3. This is why your memory benchmarks score higher when the memory is clocked at 133MHz instead of 100MHz. For maximum performance, you would also want the most aggressive memory timings that your RAM can handle.

Let it also be known that the FSB limitations of the AMD chips was attributed to the KX133 or KT133 chipset (which failed at ~118MHz DDR). For the chipsets verified for 133MHz operation (KT133A, AMD760, AliMagic...) both Athlon-B's and Durons will gladly run at a FSB of 133MHz, so long as they can handle the final clock speed. Just look around this forum. There are more than a few users doing this.


I hope this clears up some misunderstandings anyone may have had.

--------
I have not yet begun to procrastinate.
April 25, 2001 9:53:45 AM

i have the same mobo, i use pc133, whith the fsb set to 112 using the dip switches on the mobo. the memory is reported in sandra professional2001e as being 149MHz. i assume this is hostclk +33 (i think this is how it manages to run the ram at 133) the total should be 145 i am assuming the extra 4MHz is some sort of a %error by sandra or the mobo. am i mistaken or on the right tracks. and if your fsb is at 118 whats with the 133 report by sandra all about?

every thing is personal when your a person
April 25, 2001 10:07:38 AM

"a known VIA 133 story" i have the same chipset and can' get the fsb over 112 using the dip switches on mobo, however i can get it to 118 if i use a software utility such as CPUCOOL this lets me change the fsb from within winnows. i know i can go higher but it is unstable as i am only using a standard cheapo fan. my brother with the same set up (ga7zm pc133 athlon 1GHz) is using a much better fan and gets his all the way up to 124 although a little unstable after 8-9 hours. the setting do work as sandra reports improved benchmarks.

every thing is personal when your a person
Anonymous
a b à CPUs
April 25, 2001 10:31:06 AM

Bartleby saying the same thing
April 25, 2001 11:07:48 AM

Bartleby is correct, the trick with VIA KT133 chipset and PC-133 RAM is just running memory async. That's really old technology, even VIA's old MVP3 SS7 chipset was capable of doing that (running memory and FSB asynchronously). I guess just Intel hasn't invented it yet :)  BTW, specially Durons are pretty sensitive about system's memory bandwidth (cause of small L2 cache), using PC-133 memory instead of PC-100 may boos performance in some apps (quake3) up to 15-20%.
April 25, 2001 1:06:50 PM

hey its just the speed rating, the max (official) speed your memory can run at. and in your case it is restricted by the chipset/cpu. if it is running at 100 MHz, so is your memory. you copuld use the same memory if you upgrade to a Athlon-C with 133 MHz (or 266 MHz if you use DDR) FSB.

if you have a decent board you could actually run your cpu faster than its rated speed of 100, maybe even faster than 133 if you do it properly. in this case not only your cpu/chipset will be overclocked, you memory will be overclocked as well.

its like you sports car is capable of going 150 miles/hr but you are driving at 50!

<font color=blue>die-hard fans don't have heat-sinks!</font color=blue>
April 25, 2001 1:13:55 PM

TBird,

The "133" in KT133 means memory speed at 133mhz. Using PC100 memory in an Athlon or Duron will slow system performance. To get the most of either chip you need PC133 memory (with the KT133 chipset).

The BIOS setting to look for is DRAM SPEED. In my Abit KT7-RAID I have 2 choices: hstclk, or hstclk+pcibus.

Hstclk is 100mhz, hstclk+pcibus is 133mhz. Benchmarking with Sandra showed about a significant increase in memory benchmarks when running the memory at 133mhz.

My system bus is still at 100Mhz.

The ability to run the memory faster then the FSB is one of the many things that swayed me away from Intel to AMD. It would be nice if I could do the same with my three Intel machines. But they are all limited to 66mhz FSB, so PC100 memory is more then what I need there (even though they are overclocked to 75Mhz).

I am surprised at the arrogance of Raystonn. The problem with many "experts" is the developement of "tunnel vision", the inability to see things slightly out of your immediate center of vision. Intel is the apparent center of his world.

Check out his signature. It says it all. He is the "center of your digital world". But he doesn't see the details to the left or right of him, only what is directly in front of him.

In preparation for the verbal bashing to come, I have no brand loyalty, and could care less about which companies chip is in my machine. There are advantages and disadvantages to both Intel and AMD. AMD simply had more advantages for ME for my last upgrade. My next upgrade at the end of the summer could be an Intel chip if they get their prices in line with AMD (but never a P4).

<font color=blue>This is a Forum, not a playground. Treat it with Respect.</font color=blue>
Anonymous
a b à CPUs
April 25, 2001 1:18:18 PM

My understanding of the computer world goes like this:

The FSB is the bus between the CPU and the northbridge.
The memory also connects to the northbridge not directly to the CPU.
Therefore, it is entirely possible to design a northbridge that can clock the CPU and memory separately. I also have my FSB set at 100MHz and memory running 133MHz. I'm not arguing that this is an ideal situation. But until you started posting, every bit of tech advice I have seen and every benchmark I and other users have tried supports the fact this can be done on modern chipsets.
Anonymous
a b à CPUs
April 25, 2001 2:41:34 PM

Thanks man..

And hey morons who think im stupid about this thread huh?

Well,
i sure dont look stupid anymore huh...

It can run at 133 morons!

I knew it!
=)


-- They have found a way to harness the power of a thunderstorm and expell it with great force!--
Anonymous
a b à CPUs
April 25, 2001 5:51:24 PM

Sorry, wrong didly wrong. The memory and bus can run asyncronously on most new chipsets, for P3's and Thunderbirds. On some systems, you can even run the memory faster than the bus. It simply depends on your chipset, and the features it supports.

KT133 runs memory at 133MHz with a 100MHz DDR bus. This gives much better performance than 100MHz memory with a 100MHz DDR bus.

VIA KT133: 100MHz DDR system bus, PC100/PC133 memory support
VIA KT133A: 100/133MHz DDR system bus, PC100/PC133 memory support
(this means either with either! - it's possible to be on 133MHz bus / PC100)
AMD 760: 100/133MHz DDR system bus, PC1600/PC2100 memory support

~ I know the human being and fish can coexist peacefully ~
Anonymous
a b à CPUs
April 25, 2001 5:58:23 PM

Oh, yeah, and the Athlon/Duron bus is most certainly DDR at all times, even when not using DDR memory. This is why PC133 on 100/133MHz DDR is better than PC100 on 100/133MHz DDR, simply because the bus is way ahead of the RAM speed, so buy the fastest RAM possible!

Athlon Thunderbird B Edition - 100MHz DDR = 200MHz (approx.)
Athlon Thunderbird C Edition - 133MHz DDR = 266MHz (approx.)
Duron - 100MHz DDR = 200MHz (approx.)

The bus works at DDR <b><i>all the time<i></b>. Am I not making myself clear here? Even with SDRAM, your bus is this fast! This is of course a good thing, more FSB to deal with AGP/PCI transfers and the like (the memory bus and expansion bus share the fsb)

~ I know the human being and fish can coexist peacefully ~
April 25, 2001 7:24:12 PM

Quote:
Let it also be known that the FSB limitations of the AMD chips was attributed to the KX133 or KT133 chipset (which failed at ~118MHz DDR). For the chipsets verified for 133MHz operation (KT133A, AMD760, AliMagic...) both Athlon-B's and Durons will gladly run at a FSB of 133MHz, so long as they can handle the final clock speed. Just look around this forum. There are more than a few users doing this.

I'm one example. I can run my a 1Ghz 'B' Athlon (100Mhz FSB) @ 1.33Ghz (133Mhz FSB) at the same multiplier w/o voltage tweaks.
April 25, 2001 8:36:49 PM

That's not really relevant. If the CPU is communicating with the Northbridge over a frontside-bus that is operating at 100MHz, then it doesn't matter much at what speed your memory or Northbridge bus is operating. You will not be able to pipe data over that frontside-bus, and hence to and from the CPU, at a rate greater than 100MHz.

-Raystonn

-- The center of your digital world --
Anonymous
a b à CPUs
April 25, 2001 9:59:07 PM

it seems some people here still don't think ram speed can run at a different clock speed as fsb. obviously it does. i see no reason why they would make a chipset (kt133) that supports pc133 when the athlon-b has only 100mhz bus (200 ddr). it does utilize the extra 33mhz since at 133mhz, the bandwidth of the ram is still lower than the fsb due to the ddr.
Anonymous
a b à CPUs
April 25, 2001 10:21:10 PM

<b>Raystonn</b>, Lets have a math lesson, seeing as you like to talk numbers (read: see <A HREF="http://forumz.tomshardware.com/hardware/modules.php?nam..." target="_new">here</A>)

for Athlon/Duron with a 100MHz DDR FSB and memory run asynchronously at 133MHz, you have the following theoretical bandwidths:
FSB: 100MHz * 2(ddr) * 64bit = 1600MB/s
memory: 133MHz * 1(sdr) * 64bit = 1064MB/s

last time I checked, 1600 > 1064.

Therefore the Athlon platform can take advantage of PC133 memory while keeping the cpu bus within spec. The information you provided is relevant to P3 chipsets where the cpu FSB is a SDR bus, and an increased memory bandwidth does not have as huge an increase in cpu performance, but is not the case for the Athlon/Alpha EV6 bus.

This has also been ratified by countless benchmarks on this site as well as other well know hardware sites.

Please get your facts straight next time :smile:

--------
I have not yet begun to procrastinate.
April 25, 2001 10:24:01 PM

The memory may very well be running at 133MHz. The Northbridge may very well be reading from memory at 133MHz. But the Northbridge must hand off data to the frontside bus in order to give it to the CPU. This will always be limited to the speed of the frontside bus, which in this case is 100MHz. Again, peripherals using DMA access, such as video cards, will not be using the frontside bus and hence will be able to use the memory at the 133MHz Northbridge bus speed. But this has nothign to do with yoru actual CPU accessing memory.

-Raystonn

-- The center of your digital world --
April 25, 2001 10:38:27 PM

Bartleby,

First off, when you run memory asynchronously, you incur _extra_ latency. The data is not necessarily going to be ready precisely when asked for. Second, if you have a DDR FSB then yes, you'll be able to cover the bandwidth of the PC133 memory sufficiently. But it's a bit of a waste to have a FSB capable of using PC1600 memory and only give it PC133 memory, coupled with asynchronous timing issues that increase latency. A straight up 133MHz FSB will always be faster than this, especially in terms of latency.

-Raystonn

-- The center of your digital world --
Anonymous
a b à CPUs
April 25, 2001 11:54:55 PM

LOL
see
im not so dumb after all!
Geeze
all u are arguing now!
=P

All i know is..
I did benchmarks with my bus at normal 100MHz (DDR) 200..
And...
I left in CMOS
my mem at 100MHz
i did a mem benchmark in SiSoft Sandra
then.
i rebooted
set it to 133MHz
rebenchmarked
and the scored were WAY higher

I know its running at 133Mhz
i know it is

Those of u who think its only 100MHz bus ur wrong!
its 100 DDR this giving it 200



-- They have found a way to harness the power of a thunderstorm and expell it with great force!--
April 26, 2001 12:42:49 AM

Yes, you have the equivolent of a 200MHz bus at your disposal. You are using 133MHz ram with it. You are correct in that you are using it at 133MHz. I missed the DDR part of the FSB earlier. However, your latency is going to be pretty poor with that design.

-Raystonn

-- The center of your digital world --
April 26, 2001 2:40:56 AM

Not the latency thing again. I thought we had this covered in the RDRAM Vs. DDR SDRAM arguement.
In reply to: "Geeze, for someone labeled as an "addict" you sure don't know that much", talk about the blind leading the blind.

- Tempus fugit donec vestrum relictus tripudium. Autem amor praeterea magis pretium.
April 26, 2001 4:52:01 AM

:lol:  </b>LOL!!!</b>
Anonymous
a b à CPUs
April 26, 2001 5:27:55 AM

Good one

LOL



-- They have found a way to harness the power of a thunderstorm and expell it with great force!--
Anonymous
a b à CPUs
April 26, 2001 6:49:11 AM

He telling you something but you are not listening. The memory can run at a 133 gizillion mhz but if the chip is 100 then guess what its gonna be a 100 fsb not 133 gizillion mhz. Geeze you can get it threw yer heads? He cannot run 133 effective fsb its only 100 fsb chip. Thats why tbird you can only clock up to 118 fsb before it gets unstable. It is because the chip is 100 and the memory has to run a 100 even though it is 133. If you stick ddr in there itll only run at 200 fsb not 266 even if its 266 graded.

SPUDMUFFIN

<font color=blue>Just some advice from your friendly neighborhood blue man </font color=blue> :smile:
April 26, 2001 6:58:11 AM

ok, for anyone and everyone interested, i will attempt to clairfy the AMD FSB DDR CPU RAM question, and any other porblem relating to some sort of three letter acronym or TLA

1. For the most part, all but the newest AMD based chipsets do not support DDR sdram, KT133, KX133, and so on, so RAYSTONN's suggestion that pc1600 (DDRSDRAM) is at the disposal of these chipsets is untrue. DDR memory is only supported in the newer AMD760 and equivalent chipsets.

2. The 100mhz FSB is doubled, resulting essencialy a 200mhz FSB, which can take advantage of memory running at 133 mhz. Yes the latency does become an issue, but there are companies out there that make PC133 SDRAM with CAS 2 modules. VERY GOOD CHOICE if you can afford it. Some can even be overclocked past 150 mhz, which a 200 mhz FSB is still able to handle.

3. TOMSMART, the reason you're showing 4 points higher is not an error of percentage by any means. Setting the doubled FSB aside for the moment, we'll look at the core front side bus, which is 100 mhz. When overclocking the ram to 133 they do not simply add 33 mhz to the front side bus to give it this increase. A multiplier is used. to attain a 133 mhz memory bus from a 100 mhz FSB, the FSB is multiplied by 1 and 1/3. As you increase the FSB you don't just add 33 to the final FSB speed, you must multiply your overclocked FSB by the regular 1 and 1/3. Check your numbers, the math for it works.

4. AMD and Intel based chipsets are not the same. They drive cars in england too, but you'd be hard pressed to follow the rest of the world's traffic rules over there. In light, it's not safe to assume you can awnser AMD questoins with Intel answers because that math just doesn't add up. Also, once at the end of the long intel tunnel, hop off the train and read a little about AMD, maybe look at some of the benchmarks. This coming from a once hardcore Intel fanatic, who in the begining never even gave AMD a chance.


TBIRDINSIDE, you're best bet is the cheap and plentiful PC133 SDRAM, will work like a charm on your system, but if you're looking for a significant increase in performance in a world where the memory BUS is one of the biggest performance limiting factors, check out the possibility of some CAS 2 PC 150 ram from companies like Mushkin.

hope this sheds some light on the question without sounding like a jerkoff
Anonymous
a b à CPUs
April 26, 2001 7:09:28 AM

Nope sounded ok to me.

SPUDMUFFIN

<font color=blue>Just some advice from your friendly neighborhood blue man </font color=blue> :smile:
April 26, 2001 8:36:20 AM

"RAYSTONN's suggestion that pc1600 (DDRSDRAM) is at the disposal of these chipsets is untrue"

I never suggested that DDR was in fact available. I merely stated that the extra bandwidth from the double pumped 100MHz (effectively 200MHz) bus, beyond 133MHz, was being wasted.

"Yes the latency does become an issue, but there are companies out there that make PC133 SDRAM with CAS 2 modules"

Irrelevant. The latency stems from the asynchronous system. The data will not necessarily be ready when it's asked for as in a properly designed synchronous system.

-Raystonn

-- The center of your digital world --
April 26, 2001 8:40:15 AM

"Not the latency thing again. I thought we had this covered in the RDRAM Vs. DDR SDRAM arguement."

It's a well known fact that memory running asynchronous to the CPU and FSB has more latency than memory in synchronous systems. Attempting to throw insults at me doesn't change the laws of physics.

-Raystonn

-- The center of your digital world --
Anonymous
a b à CPUs
April 26, 2001 8:56:12 AM

There are two effects here. 133MHz over 100MHz memory speed (positive) and increased latency (negative). And behold, the first is stronger, get over it. Of course PC1600 at 2x100MHz is ideal to fill a 2x100MHz CPU bus. But for those who don't need a new mobo and DDR memory, PC133 still beats PC100 on performance.

Very much the same story is the (DDR) SDRAM vs RAMBUS story about speed vs. latency...

Kjella
April 26, 2001 8:58:58 AM

a heated debate indeed

"If you run a 100MHz bus with DDR (effectively 200MHz) you should use PC1600 ram. If you run a 133MHz bus with DDR (effectively 266MHz) you should use PC2100 ram. If you are running PC2100 ram on a 100MHz bus with DDR, it's being underclocked and used as PC1600 ram"

This is a completely useless suggestion for the system in question, as it is not compatible with DDR ram. I wish it was. Basically, what I'm trying to give the guy the best options for HIS current situation. Telling the guy he wants DDR ram when his system doesn't support it is some pretty drastic misinformation.

And yes, the asynchronous system has it's flaws, but the lower the latency of your RAM, the more negligible they become. Point in case, running the ram at 133 mhz shows noticeable performance gains from 100 mhz. If the asynchronicity were that much of an issue, there would be no point in bringing the memory bus up from 100 mhz. It would be nice to be able to run the core fsb at 133 mhz, thus eliminating any of the above said issues, but when it can't be done you've got to settle for the next best thing.
April 26, 2001 9:11:23 AM

No offence intended, I'm just trying to give the best advice going by the system in question.
!