ACTUAL G5 front side bus speeds?

[Timelessblur]

Just read an interesting article on tomshardware.com which discusses dual channel RAM and what bandwidth differences it gives. For systems without on board memory controllers or ultra fast DDR buses like the G5 the RAM is held back by the FSB of the processor. So in the case of an Athlon XP running at 200MHz using DDR400 in dual channel configuration would only provide 3.2GB/s of bandwidth rather than the 6.4 we see on the G5 and Opteron systems.
The G5 does not have this problem its FSB can easily soak up the full throughput of dual channel DDR400 and apple could have increased the RAM spec to DDR500 and it would still have been fully utilised.

I might like to point out that the G5 computer are still only running DDR not DDR2 mind you it is running in dual channel which the opiton does since it is on socket 940. the AMD64 that run on socket 754 can not run dual channel but due to chip articature it still can out run equivlent chips. so even with the stangle hold it was still out passing P4 running in dual channel in memory test. Remeber than amd than run on socket 754 or higher have among the highest rating for memory test.

 

[Counterfit]

You guys gave me a headache 🙁

 

[psycho bob]

I quite agree latency is an issue, but most people will never encounter its problems. For building your low cost supercomputer or editing your Final Cut Pro video utilising the internal hard drives, FW800, RAM and both processors the latency issue becomes something of a mute point because the amount of time lost is in the milliseconds rather than the seconds/minutes. I have no doubt IBM will sort this out, probably at the same time they go dual core like the Power 5 design (that is a cracking CPU).
If I was building another PC I would do as I always have and use AMD processors. We needn't even discuss Intel at the moment with their quad pumped over heating P4, any next gen processor like the G5 or Opteron will eat it for breakfast. Only Intel's aility to ramp up the clock speed has allowed them to keep face even though it has become an over complicated inprecise beast of a chip. As it is I will stick with my G5's, for art/design they are just so much more powerful than any PC system thanks to the superior OS etc.
We all seem to have forgotten the original question 😛 . If we forget about memory bandwidth, CAS, latency etc etc... the fastest FSB in the industry belongs to the dual 2.5 G5 at 1.25GHz (625x2 (DDR))

 

[psycho bob]

You guys gave me a headache 🙁

I've had more painkillers today then ever before lol. I think I will withdraw quietly 😉

 

[diamond geezer]

I wish I could begin to understand all this talk, but despite my lack of knowledge I will add my "tuppence" worth.

G5 logic boards are described in Apple's parts database as either 167MHz for the 1.6GHz machine or 233MHz for the 1.8 & 2GHz.

The 2.5GHz does not mention speed in its parts description.

Is this any help?

 

[daveL]

I might like to point out that the G5 computer are still only running DDR not DDR2 mind you it is running in dual channel which the opiton does since it is on socket 940. the AMD64 that run on socket 754 can not run dual channel but due to chip articature it still can out run equivlent chips. so even with the stangle hold it was still out passing P4 running in dual channel in memory test. Remeber than amd than run on socket 754 or higher have among the highest rating for memory test.

Does it run OS X? Does it run iLife '05? No, so who gives a hoot? I know the subject of this thread is very specific, but yet again, it has degenerated into a "my HW is better than your HW". If the HW runs Windows, who cares? Junk, crap, nada. Bottom line: Does the HW/SW platform solve your problem, is it easy to use, is it secure, is it within your budget (including your time)?

 

[Timelessblur]

Does it run OS X? Does it run iLife '05? No, so who gives a hoot? I know the subject of this thread is very specific, but yet again, it has degenerated into a "my HW is better than your HW". If the HW runs Windows, who cares? Junk, crap, nada. Bottom line: Does the HW/SW platform solve your problem, is it easy to use, is it secure, is it within your budget (including your time)?

and yet again when people realize apple hardware is not the best they go to the famus We have OSX what about games. this is about the hardware face the facts the apple hardware is not the best out there.

 

[psycho bob]

and yet again when people realize apple hardware is not the best they go to the famus We have OSX what about games. this is about the hardware face the facts the apple hardware is not the best out there.

Hey come on lets look at the facts. Your saying apple hardware is not the best that is your right to do so but surely you cannot be basing that whole premise on RAM latency. At the end of the day you can use and think what ever you like, we all have our own opinions. Mine is that speed asside (that can be discussed and argued until hell freezes over) the G5 is the best desktop out there bar none. From its build, looks, ease of use and overall performance it is an unbeatable package and that is before you consider the OS and software. Try putting together a top of the line Opteron system for below £2000 (or $ equivalent). At the end of the day the Opteron is essentially a server CPU or one for very highend workstations, I personally do not see it as a competitor to the G5 if anything it goes after the IBM Power 5. The G5 is a readily accessible 64bit CPU which is far more useable and faster in it's target market then the Athlon 64FX and anything Intel can muster.
At the end of the day people couldn't really give a toss about FSB, latency etc, they just want a fast computer that is reliable and allows them to use the software they want. Most of the people I know use PC's and are pretty well up in technology matters and every single one without fail has been impressed with the G5, that doesn't mean they will buy it but they recognise it for what it is a great piece of engineering. The arguement always seems to end up with 'what about games'... well what about them? The mac has never really been a gaming machine but I've never had any trouble running the latest ones that are released and thanks to the dual processor architecture I can whack everything on full have photoshop rendering in the background and everything works great, try doing that on your single CPU machine regardless of the processor.
IBM and AMD have been working closely of late developing new technologies with relation to CPU manufacture. At the end of the day the Opteron has benefits over the G5 and vice versa, both are great chips simple as that. Which you choose depends on what you do and what system you want. But to buy something over something else based on one small aspect which in normal use isn't noticeable either means your work is very specialised or you really like boasting about your on chip memory controller 😉

 

[psycho bob]

I wish I could begin to understand all this talk, but despite my lack of knowledge I will add my "tuppence" worth.

G5 logic boards are described in Apple's parts database as either 167MHz for the 1.6GHz machine or 233MHz for the 1.8 & 2GHz.

The 2.5GHz does not mention speed in its parts description.

Is this any help?

Do you have a link I'd be interested in reading that information?

 

[Timelessblur]

Hey come on lets look at the facts. Your saying apple hardware is not the best that is your right to do so but surely you cannot be basing that whole premise on RAM latency. At the end of the day you can use and think what ever you like, we all have our own opinions. Mine is that speed asside (that can be discussed and argued until hell freezes over) the G5 is the best desktop out there bar none. From its build, looks, ease of use and overall performance it is an unbeatable package and that is before you consider the OS and software. Try putting together a top of the line Opteron system for below £2000 (or $ equivalent). At the end of the day the Opteron is essentially a server CPU or one for very highend workstations, I personally do not see it as a competitor to the G5 if anything it goes after the IBM Power 5. The G5 is a readily accessible 64bit CPU which is far more useable and faster in it's target market then the Athlon 64FX and anything Intel can muster.
At the end of the day people couldn't really give a toss about FSB, latency etc, they just want a fast computer that is reliable and allows them to use the software they want. Most of the people I know use PC's and are pretty well up in technology matters and every single one without fail has been impressed with the G5, that doesn't mean they will buy it but they recognise it for what it is a great piece of engineering. The arguement always seems to end up with 'what about games'... well what about them? The mac has never really been a gaming machine but I've never had any trouble running the latest ones that are released and thanks to the dual processor architecture I can whack everything on full have photoshop rendering in the background and everything works great, try doing that on your single CPU machine regardless of the processor.
IBM and AMD have been working closely of late developing new technologies with relation to CPU manufacture. At the end of the day the Opteron has benefits over the G5 and vice versa, both are great chips simple as that. Which you choose depends on what you do and what system you want. But to buy something over something else based on one small aspect which in normal use isn't noticeable either means your work is very specialised or you really like boasting about your on chip memory controller 😉

fine you want to play that game your right that the opteron is a server chip but the AMD 64 line is a normal computer chip that is still out running the G5

For software not going ot using games and besidce the fact I like plently of games the mac does not have. Besides that I have over 1k software that I use that is not games that oh yeah the OSX does not have. I am also planing on adding autocad to my desktop with in the next year or so and oh yeah macs sucks when it comes to cad work. This program are profection level aps so utter lack of software is a vaild reason.
Depending on what I am doing depends if I noticed the extra power some stuff it is very noticble some stuff the computer is overkill.
For the mess I put up with the OS no dont really put much time in it and I know my computer is clean I know how to take care of a computer . For most stuff most argument that Mac users give I can tell you guys over blow it.
I could start poking holes in the Imac and point out I paid less and my computer is more powerful. I wanted to stay out of that.

 

[solvs]

I wish I could begin to understand all this talk, but despite my lack of knowledge I will add my "tuppence" worth.

G5 logic boards are described in Apple's parts database as either 167MHz for the 1.6GHz machine or 233MHz for the 1.8 & 2GHz.

The 2.5GHz does not mention speed in its parts description.

Is this any help?

Um... what? Ok, the old 1.6 used to use 333MHz DDR RAM (which runs at 167MHz rising and falling, DDR = double data rate). But it required you to run 2 of the same sticks together for a dual channel rate of 666MHz, but it still had an 800MHz FSB. The current iMacs have a slower FSB on their G5s, but the 2.5GHz G5 is running a 1.25GHz FSB, half the speed of the CPU.

This whole argument is still silly though. Even with DDR2 (which has a higher latency BTW, so it can be slower at times even), or overclocked DDR RAM running at over 400MHz, there are a ton of other factors that effect overall speed.

To answer the original question, the highest rated G5 (at 2.5GHz) has a FSB of half the CPU speed... 1.25GHz. The RAM is 400MHz DDR (rising and falling 200MHz) running in dual channel, for an effective speed of 800MHz. Whether it's faster than other chips is debatable. For some things it is, for others it isn't. Sorry, but it's funny we're still talking about it.

I need to get back to work. 😛

 

[brap]

...(snip)...
I could start poking holes in the Imac and point out I paid less and my computer is more powerful. I wanted to stay out of that.

Horses for courses.

You want your Windows PC? Fine, it's cool, good luck, hope the CAD apps work well for ya.

The fact is Macs are simpler, package-for-package. Not everybody can build a PC themselves, very few people can look after the Windows OS properly. The hardware too, x86 develoment has so much more R&D pushed into it it's no wonder it moves on quicker. If you think about the scale of the thing, isn't it remarkable that Apple is still in business, let alone pushing out feasible, powerful, affordable Mac minis, and Superclusters of G5s? You don't seem to be "Getting" this argument - which is fine, since the thread title is all about that. Just perhaps be aware some people will argue this case.

My real question is - how does it feel to be crusading against the poor, uneducated Mac-users? "Zealots", if you will?

 

[psycho bob]

fine you want to play that game your right that the opteron is a server chip but the AMD 64 line is a normal computer chip that is still out running the G5

For software not going ot using games and besidce the fact I like plently of games the mac does not have. Besides that I have over 1k software that I use that is not games that oh yeah the OSX does not have. I am also planing on adding autocad to my desktop with in the next year or so and oh yeah macs sucks when it comes to cad work. This program are profection level aps so utter lack of software is a vaild reason.
Depending on what I am doing depends if I noticed the extra power some stuff it is very noticble some stuff the computer is overkill.
For the mess I put up with the OS no dont really put much time in it and I know my computer is clean I know how to take care of a computer . For most stuff most argument that Mac users give I can tell you guys over blow it.
I could start poking holes in the Imac and point out I paid less and my computer is more powerful. I wanted to stay out of that.

Try and pick up an earlier version of Autocad around 2000 or the version before. It seems to get more and more bloated with every release, 2000 was good once they ironed out the bugs of the initial launch product. I have a PC and it chugs along fine never had any issues with it other than a failed hard drive. Like I said you use what best fits the work you do.
I have no problems with PC's at all but for the design and photography I do would I swap my G5 for an Athlon or Opteron based system... no, that is my choice. Having invested in Apple's Pro Apps (annoyingly before they released the production suite), Quark Xpress, Adobe Creative Suite, Macromedia Studio etc it would be foolish to jump platforms and I've had no reason to even give it thought. I've used macs since the LC days and will continue to use them. The Athlon 64 is a very good chip and beats the P4 and G5 in some benchmarks just as they beat it in others. I couldn't really care less.
I assume you are a PC user first and foremost? Why does it matter to you what we think, at no point in this entire thread have I or anyone else stated the G5 is the best processor. All we wanted to clarify that the fastest FSB currently available belongs to the G5. Will it always be like that? Probably not. And as people have pointed out there are so many other things that go to creating a fast, but above everything, reliable compter.

 

[Timelessblur]

Try and pick up an earlier version of Autocad around 2000 or the version before. It seems to get more and more bloated with every release, 2000 was good once they ironed out the bugs of the initial launch product. I have a PC and it chugs along fine never had any issues with it other than a failed hard drive. Like I said you use what best fits the work you do.
I have no problems with PC's at all but for the design and photography I do would I swap my G5 for an Athlon or Opteron based system... no, that is my choice. Having invested in Apple's Pro Apps (annoyingly before they released the production suite), Quark Xpress, Adobe Creative Suite, Macromedia Studio etc it would be foolish to jump platforms and I've had no reason to even give it thought. I've used macs since the LC days and will continue to use them. The Athlon 64 is a very good chip and beats the P4 and G5 in some benchmarks just as they beat it in others. I couldn't really care less.
I assume you are a PC user first and foremost? Why does it matter to you what we think, at no point in this entire thread have I or anyone else stated the G5 is the best processor. All we wanted to clarify that the fastest FSB currently available belongs to the G5. Will it always be like that? Probably not. And as people have pointed out there are so many other things that go to creating a fast, but above everything, reliable compter.

simple it is one thing to have an opinan it is another to basicly start saying blantly lies. When clearly most mac users dont know what htey are talking about. I rather people have correct facts instead of the famus apple BS and users who complain and refuse to see any good in PCs and MS windows

 

[Bigheadache]

All we wanted to clarify that the fastest FSB currently available belongs to the G5. Will it always be like that? Probably not. And as people have pointed out there are so many other things that go to creating a fast, but above everything, reliable compter.

Well congrats to the marketing types at Apple, Intel, and AMD for making a complete meal out of this.

Anyway, to get back on topic, a FSB is traditionally the connection from the memory controller to the CPU. In an AMD AThlonXP, G5, and an Intel, the memory controller is in the northbridge chip which means the FSB also doubles up as part of the system bus.

On an AMD64 it is different as the memory controller is internal to the CPU die. Therefore, the FSB must be the fastest of all chips because as an internal on chip component it operates at the CPU's native speed. The Hypertransport link on an AMD64 is the system bus, not the FSB.

So in answer to the OP's question, your professor is correct. The fastest FSB on a G5 is 1.25GHz but the fastest AMD64 FSB available is 2.6GHz (the FX55).

Aside from the integrated memory controller and 64bit extensions (which aren't used on Windows), the A64 is mainly an enhancement of the AthlonXP. Given that, we can surmise that its the integrated memory controller which is the main reason for its excellent performance vis a vis the AthlonXp, so I for one hope that an integrated memory controller appears somewhere on the PowerPC roadmap.

 

[psycho bob]

I think the 1MB of L2 cache helps somewhat as well.
What I do find intriguing though is the confusion within the industry itself. A PC site that I trust and is very expansive www.tomshardware.com have detailed reviews of all the athlon products including the new FX55. They never state the FSB. Where reference can be found for the FX series it is stated as being 400MHz (after multiplier) http://www.amdboard.com/athlon_64_fx-55.html http://www.amdreview.com/reviews.php?rev=fx-55-4000
On a personal level (I'm not an IT expert) I don't understand how having the connection between CPU and RAM running at processor speed can be of such a great benefit when the finite speed of the DDR400 in dual channel configuration is 800MHz. I understand the latency issues and how more than with an other CPU having low latency DIMMs help but it can't get there any quicker than the clock speed the memory operates at.
One issue with having the memory controller built in is the fact you ae forced to use specific RAM. A motherboard maker cannot simply design the board to use DDR2 for example the CPU has to support it. I beleive when the FX was originally introduced is supported 266/333 and now adds 400 to the mix. If they want to add DDR2 or faster they have to redesign the whole die.
I need more pain killers 😱

 

[Mav451]

psycho bob: Regurgitating what you read on the Internet doesn't show that you've learned anything. Second, for the love of god, do NOT go to TomsHardware to "learn about AMD". Tom's was notorious for skewing their benchmarks toward Intel. If you want to learn about AMD chips, go to reputable sites like The Tech Report, [H]ardOCP, Anandtech, or Xbit Labs.

You also keep talking about how latencies don't mean jack--until you actually see the difference first hand, you will never understand its significance. Why don't you go find someone with an A64, and have them show you the difference between 3-3-3-8 RAM and 2-2-2-5. Trd2 and cas2 equates to literally a 10-12Mhz increase in memory FSB (e.g I get the same memory bandwidth at 200Mhz with those latencies as I would get at 210-212 with the much looser settings). While memory bandwidth's impact is most significant in gaming, other applications like Divx/MPEG encoding could use it>> it means shaving off seconds, to minutes, to hours even. In PShop it could mean waiting 10-12 less seconds on applying a filter.

Regarding your misunderstanding of FSB, yes, while certain sites would claim that the FX-55 or the FX-series is running at 400Mhz (which means 400 * 8 = 3.2GB/s of memory bandwidth), that couldn't be farther from the truth.
http://www.hardocp.com/article.html?art=Njc1LDI=

B/c of having not only a dual-channel memory controller, but an integrated one, it achieves nearly 6GB/s of memory bandwidth. Running at "only 400Mhz", it far exceed Intel's offering on the 3.46EE, which has an "FSB" of 1066Mhz. Not on the other hand, when I run at "only 400Mhz" or 430Mhz to be exact, my results are much different than what an FX would get. B/c the Bartons do not have an IMC, Bartons are already inherently capped in memory performance and also in CPU performance. What some people forget is that the newer K8 core (Opteron/FX/Athlon64) chips are still essentially a modification and improvement of the Barton (K7) core. Reduced latencies have meant improving anywhere from 50% to 200% of the performance a Barton would have at the same clockspeed. I can tell you that if I had an IMC with my Barton, @ 2.55GHz, it would be in the range of singlehandedly equalling or exceeding dualG5 systems. However, the reality is that w/o that IMC, my Barton is closer to a single G5 (1.8-2.0) range.

 

[wrldwzrd89]

psycho bob: Regurgitating what you read on the Internet doesn't show that you've learned anything. Second, for the love of god, do NOT go to TomsHardware to "learn about AMD". Tom's was notorious for skewing their benchmarks toward Intel. If you want to learn about AMD chips, go to reputable sites like The Tech Report, [H]ardOCP, Anandtech, or Xbit Labs.

You also keep talking about how latencies don't mean jack--until you actually see the difference first hand, you will never understand its significance. Why don't you go find someone with an A64, and have them show you the difference between 3-3-3-8 RAM and 2-2-2-5. Trd2 and cas2 equates to literally a 10-12Mhz increase in memory FSB (e.g I get the same memory bandwidth at 200Mhz with those latencies as I would get at 210-212 with the much looser settings). While memory bandwidth's impact is most significant in gaming, other applications like Divx/MPEG encoding could use it>> it means shaving off seconds, to minutes, to hours even. In PShop it could mean waiting 10-12 less seconds on applying a filter.

Regarding your misunderstanding of FSB, yes, while certain sites would claim that the FX-55 or the FX-series is running at 400Mhz (which means 400 * 8 = 3.2GB/s of memory bandwidth), that couldn't be farther from the truth.
http://www.hardocp.com/article.html?art=Njc1LDI=

B/c of having not only a dual-channel memory controller, but an integrated one, it achieves nearly 6GB/s of memory bandwidth. Running at "only 400Mhz", it far exceed Intel's offering on the 3.46EE, which has an "FSB" of 1066Mhz. Not on the other hand, when I run at "only 400Mhz" or 430Mhz to be exact, my results are much different than what an FX would get. B/c the Bartons do not have an IMC, Bartons are already inherently capped in memory performance and also in CPU performance. What some people forget is that the newer K8 core (Opteron/FX/Athlon64) chips are still essentially a modification and improvement of the Barton (K7) core. Reduced latencies have meant improving anywhere from 50% to 200% of the performance a Barton would have at the same clockspeed. I can tell you that if I had an IMC with my Barton, @ 2.55GHz, it would be in the range of singlehandedly equalling or exceeding dualG5 systems. However, the reality is that w/o that IMC, my Barton is closer to a single G5 (1.8-2.0) range.

Your post shows that Apple could learn some things from AMD about how to design their computers. How much of it could be applied to the G5 design is debatable. It seems that many, if not all, of the improvements Apple could make based on knowledge of AMD's design revolve around memory - is this correct?

 

[ajkst1]

So basically this thread crumbled into a "My FSB is better than your FSB."

What is the fastest FSB? Is it the 1.25 Ghz on the 2.5 Ghz G5 or something from AMD? Am I right or is my prof right?

 

[psycho bob]

If I'm wrong I don't mind I'm not trying to be clever just to learn. At no point did I say that latency wasn't important. What I did say was that unless you compared two systems side by side doing very repetitive tasks the difference wouldn't be noticeable to the average user. The article you linked says basically that.
What I asked but still haven't found an answer to is how using dual channel channel DDR400 RAM giving you effectively 800MHz can be made any quicker on the athlons processor speed FSB compared to the G5's 1.25GHz FSB. The latency as I understand is not only in the RAM but also the path it has to take to the CPU, this is where the FX has the advantage. The system controller on the G5 doesn't operate like older North Bridge designs and operates a point to point architecture with all main subsystems having direct access to the RAM. As the FX is linked directly to the RAM does that mean all memory access has to be diverted via the CPU?
Both the AMD K8 cores and the G5 have memory bandwidth of 6.4GB/s as they essentially operate in the same way the only difference being the route the data takes. So are we saying that the only real difference between the G5 and K8 is the reduced latency of the latter?
In which case the question becomes what real world advantages does the reduced latency have? You say it equates to around 12MHz would the difference then not be made mute if apple simply used faster DDR memory than the AMD systems?
So before you blow my head off and criticise everything I've said just let me reiterate I'm just trying to understand this myself. I'm not sticking up for apple or IBM. Any info you can provide is most welcome 🙂

 

[psycho bob]

So basically this thread crumbled into a "My FSB is better than your FSB."

What is the fastest FSB? Is it the 1.25 Ghz on the 2.5 Ghz G5 or something from AMD? Am I right or is my prof right?

It would appear your prof at least on paper. What I'm trying to find out is what real world difference the super fast FSB for RAM on the AMD chip has when the DDR400 memory is so much slower.

 

[diamond geezer]

Do you have a link I'd be interested in reading that information?

There is no information to read, it's just a part name.

I can't send you the link, it's for Apple Techs only.

 

[simie]

http://www.amd.com/us-en/Processors/ProductInformation/0,,30_118_9485_9488^9564~74984,00.html

You folk might want to read this.

😎

 

[psycho bob]

http://www.amd.com/us-en/Processors/ProductInformation/0,,30_118_9485_9488^9564~74984,00.html

You folk might want to read this.

😎

The architecture data and comment was interesting. Do you have a link for the Athlon FX white paper? Hopefully that will go into greater detail about the specific benefits and perhaps put some figures to the words. I'll have a lok for it myself if I get a chance.

 

[Bigheadache]

The architecture data and comment was interesting. Do you have a link for the Athlon FX white paper? Hopefully that will go into greater detail about the specific benefits and perhaps put some figures to the words. I'll have a lok for it myself if I get a chance.

When you talk about the 6.4gb/s bandwidth, you are actually talking about a purely theoretical capability. If you go to PC forums and see what memory scores people are getting using SANDRA or any other diagnostic tool, its not unusual for socket 939 A64 owners with dual channel DDR400 to get 6000mb/s. But on Intel systems with the same memory people are only getting 4500-5000mb/s when theoretically both should be getting 6.4gb/s. The theoretical FSB bandwidth of an Intel 1066FSB chip is actually something like 8.4gb/s.

With scores like that, its obvious that AMD don't see a compelling need to move to DDR2. Sure its a disadvantage that to provide DDR2 support the chip has to be redesigned, but AMD excels because of the efficiency of its integrated memory controller not by ramping up memory speeds. As I said previously, I hope this is something which is considered for the G5 at some stage.

As for latencies, they aren't important on a Intel chip, and very important on an AthlonXP. However, on an A64 they aren't really important as long as you can get 1T command rate. if you are stuck with 2T then its costing you about 20-30MHz in RAM speed. CAS timing does not have a major impact.