IBM's G5 FSB

[Ffats]

I was intrigued by the first thread on here, so did a little research (however, it's coming from the Press machine that is Apple.com)
Reference Page Here (http://www.apple.com/g5processor/architecture.html)

The G5 features a scalable design that enables it to run at clock speeds up to 2GHz. This represents a 600MHz jump, the largest in PowerPC history, over the fastest G4 processor at 1.4GHz. But all the megahertz in the world wouldn’t mean squat if the G5 were stuck talking to the rest of the machine at the 167Mhz bus speed of the Power Mac G4. That’s why the G5 features two unidirectional 32-bit data paths: one traveling into the processor and one traveling from the processor, unlike previous designs. Its frontside bus works at speeds up to 1GHz for an astounding 8 GBps of total bandwidth. That makes it 200MHz faster than even the latest Intel 875 chipset, which sputters out at 800MHz.

I believe this means a dual-pumped FSB interface, as it says one upstream one downstream... I apologize, as I'm not very familiar with FSB tech talk at the moment.

I'm not sure why they use the words "Up To" - Isn't it supposed to run at 1ghz all the time (or 99% of the time).. [Watch out for Opinion]And 800mhz FSB is nothing SPUTTERING!

[Chowdy]

lol. "sputtering". Sketchy marketing is funny :D

[method().man]

Originally posted by Ffats
I was intrigued by the first thread on here, so did a little research (however, it's coming from the Press machine that is Apple.com)
Reference Page Here (http://www.apple.com/g5processor/architecture.html)



I believe this means a dual-pumped FSB interface, as it says one upstream one downstream... I apologize, as I'm not very familiar with FSB tech talk at the moment.

I'm not sure why they use the words "Up To" - Isn't it supposed to run at 1ghz all the time (or 99% of the time).. [Watch out for Opinion]And 800mhz FSB is nothing SPUTTERING!

Their low end model comes with 800 MHz FSB and ramps up to 1GHz FSB for their high end.

[Maxvla]

i'd love to see apple's chips do 1200mhz+ bus speeds like kunaak's p4 at ~314mhz fsb.

basically they are taking the same chip and overclocking it by way of fsb instead of multiplier like intel does.

[method().man]

Originally posted by Maxvla
i'd love to see apple's chips do 1200mhz+ bus speeds like kunaak's p4 at ~314mhz fsb.

basically they are taking the same chip and overclocking it by way of fsb instead of multiplier like intel does.

You know, I think you might be right. If you divide the clockspeed of their low-end G5 by 200 - the low end's fsb, you get a multiplier of 8. Strangely enough, if you use that multiplier with the other two G5s, you get exactly their clockspeed.

[imgod2u]

The ElasticIO bus of the PPC970 is a unidirectional point-to-point bus. It uses DDR signaling (2 signals per clock) and there are 2 unidirectional channels (one each way). The clock is 1/4 of the CPU clockspeed, so for a 1.8GHz PPC970, you'd have an FSB of 450MHz DDR (900 effective). For a 2.0 GHz PPC970, you have an FSB of 500MHz DDR (1000 effective).
The IO bus is suppose to scale with the processor speed. It's 32-bits wide and serial (much like Hypertransport) but with low-latency. At 500MHz DDR, it provides 4.0 GB/sec in each direction for a total of 8 GB/sec of maximum bandwidth.

[Mark Larson]

Originally posted by Maxvla
i'd love to see apple's chips do 1200mhz+ bus speeds like kunaak's p4 at ~314mhz fsb.

basically they are taking the same chip and overclocking it by way of fsb instead of multiplier like intel does.
Uh, no. Its nowhere near as simplistic as that. The G5's FSB runs at a quarter of CPU speed, and with DDR, at half the CPU speed. The FSB and memory speed are different, and they use DCDDR400 in the top-end model and DDR333 in the 1.6Ghz.

Higher bus speed-based models will come in the future, and let's not compare stock to overclocked, the typical defense of fanboys. :rolleyes:

BTW - the model Apple is using for the G5 is the same as the one introduced for the AthlonMP - separate busses to the Northbridge, instead of one shared bus like other designs. This design isn't that effective when the Northbridge only has one pipe to the memory though, which is why we don't see many gains with the 760MPX chipset.

[OC-Master]

BTW - the model Apple is using for the G5 is the same as the one introduced for the AthlonMP - separate busses to the Northbridge, instead of one shared bus like other designs. This design isn't that effective when the Northbridge only has one pipe to the memory though, which is why we don't see many gains with the 760MPX chipset. [/B][/QUOTE]



So basically the AthlonMP needs Dual Channel DDR to gain the performance it for maximum effieciency.

Hmm, come to think of it, running dual AthlonMPs is like each one running on PC133 Memory :D Half of DDR266 being 133.


OC-Master

[imgod2u]

Erm, no, I'm afraid that's a common misconception. While the Athlon's EV6 bus (both XP and MP) is point-to-point, it does *not* provide twice the bandwidth per point-to-point bus. It simply allows 2 separate command and data streams. The physical link between the North Bridge and processor itself is still 64-bits wide (single channel), it's just that each processor can use that same channel simultaneously and also receive data simultaneously. So, in reality, no, it does not need dual channel memory.

[Zuzzz]

sketchy??? . . yeah my junk is running at 261FSB quad pumped now. . . hehe sketchy??? HARDLY not lolol

[MetalStorm]

Now this is just me, but isnt a 1Ghz FSB pointless? I mean, if you have DDR400 in it, that gives a max bandwidth of 3200 mb/s and so in dual channel and effective 6.4 - that is not including the overhead you have with running dual channel...Now, why do you need 8000 mb/s when you can only use a maximum of 6.4 and even then thats a theoretical maximum... at least there is a point in an 800Mhz fsb, but I cant see the point of 1GHz, just up the multiplier!

That is how I see it at the moment anyway, can someone tell me if im wrong, preferably with as few flames as possible :D

[TUK101]

All that I know about this subject is that the Mac G5 commercial is hellarious :p ;) :eek: That dude flying through three different walls and into the big oak tree was a very unique idea and will sell more comps alone than the power of the G5's processor and fsb will.

[Ffats]

Originally posted by TUK101
All that I know about this subject is that the Mac G5 commercial is hellarious :p ;) :eek: That dude flying through three different walls and into the big oak tree was a very unique idea and will sell more comps alone than the power of the G5's processor and fsb will.

Odd.. I didn't think very much of that commercial. I was annoyed that Jeff Goldblum was put on as the narrator yet again. The only part I liked is the nice look of the case and that insanely overpriced display. Yes, it is overpriced :P.

[Hedgehogforprez]

Apple...overpriced....????? WHHHHHAAAAAAAAt?? ;)

[Lord_MiL]

Memory data isn't the only thing going to and from the CPU through the FSB. You never want your FSB to be saturated completely by your memory or else there's no room for I/O etc.

[countermods]

i hate macs they may be the fasteset comp out right now but they cant play any games like hl2 cs 1.6 doom 3 so fudge macs they only good for foot stands and door stoppers

[JoT]

Originally posted by countermods
i hate macs they may be the fasteset comp out right now but they cant play any games like hl2 cs 1.6 doom 3 so fudge macs they only good for foot stands and door stoppers

Macs aren't the fastest, they're just advertised as the fastest. In reality, a 486 could whoop up on a mac in 3DMark ;)

[Mark Larson]

Originally posted by JoT


Macs aren't the fastest, they're just advertised as the fastest. In reality, a 486 could whoop up on a mac in 3DMark ;)
No ****, considering there's no binary of 3DMark Penis Measuring 2001 available for OS X. :rolleyes:

[JoT]

Originally posted by Mark Larson

No ****, considering there's no binary of 3DMark Penis Measuring 2001 available for OS X. :rolleyes:

You know I'm just kidding around, Mark :p

[MetalStorm]

Originally posted by Mark Larson

No ****, considering there's no binary of 3DMark Penis Measuring 2001 available for OS X. :rolleyes:

And that macs suck...

But really, the G5 better be good, because the G4 sucked soooo badly, a friend of mine has a mac, a 700MHz G4, ok its not exactly top of the range (it was when he got it mind you...) but OMG does it suck, holy crap, I have never seen anything so slow - even comparing it to a computer bought at a similar time it looks bad, and its a "supercomputer" dont forget... contradiction of terms maybe?

[TUK101]

Macs are good for publishing software, and things of that nature. I know a lady that writes for a paper (actually she owns a small paper in my hometown) and she loves her macs. I gave her an old mac that had been given to me by my mother in law and she was estatic to be able to add it to her network. She showed me why she prefers macs and the one thing that I noticed immediatly was how easily she was able to get around and get straight to work. I have talked to a few other people that are into writing and they prefer the macs over a pc also. I know that they are not very fast at things that we pc users are used to being able to blaze through, but they are not programmed that way. They are programmed to be efficient at the things that are coded for macs specifically. The sad thing is that the majority of the programs that where coded specifically for macs (quicktime comes to mind) a mid range pc is still significantly faster still. I am not a mac fan, but I do support any kind of competition to Intel and Microsoft that there is. ;)