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Hyper Transport And FSB
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Jinkazuya
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4. October 2009 @ 13:57 |
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I know it has been somewhat discussed and was clearly explained by sammorris. But I really wanna get a better understanding of it, especially those without specific details about the FSB. So sorry for being annoying. And This is a motherboard without any info about Hyper Transport and FSB. And it only states Northbridge and Southbridge.
http://www.newegg.com/Product/Product.aspx?Item=N82E16813153149
1) Well...I know recent CPUs already have the coordinating speed with the FSB such as icore 7, as you stated, so we don't have to worry about the bottneck or the CPU outrunning the FSB. And now AMD also uses the new tech named hyper Transports, which doubles up the transfer speed. The question is some of those AMD motherboards don't specify the FSB or hyper transport speed, they only say Northbridge and Southbridge North:
Bridge AMD 780G
South Bridge AMD SB700
how do we know the speed of the hyper transport(FSB) that matches the speeds of the CPU(or maximize the CPU speed of transfer rate)? especially those backward compatible motherboards.
2) as I said in my earlier post, is this how you determine the speed of the FSB that matches the speed of the CPU to make them work more efficiently? - We first check the speed of the FSB spec of the motherboard and then compare this with the speed of the CPU. If they both match, that means the FSB can use(utilize the maximum speed of transferring data back and forth)the msx speed of the CPU to transfer data without bottleneck or the CPU outrunning the FSB.
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AfterDawn Addict
4 product reviews
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5. October 2009 @ 09:11 |
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You should really use your existing thread for this. Starting another one here is really against forum rules.
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Jinkazuya
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5. October 2009 @ 21:08 |
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But I really hope people could help because this question has been bugging me for a long time. I really hate it when I can't solve the problem esp in learning something. I do know it might be against the forum rule, but I just really hope those with knowledge about HT(AMD) could answer the question and help me eliminate my doubt.
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6. October 2009 @ 07:52 |
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Hypertransport is essentially like a front side bus, but not the same as. It performs the same tasks, but unlike FSB, it does not define CPU speed. AMDs also have a front side bus which is always 200mhz (at least in the last few years). The hypertransport is rather like the speed at which the CPU integrates with the rest of the system. This varies by CPU - due to the simplicity of overclocking AMD Black editions (you just turn the multiplier up), and the comparative lack of extreme overclocking outside that area for AMDs, I haven't spent as much time reading up on what CPUs are likely to have which HT bus.
Suffice to say, any high-performance AMD CPU is a black edition, which means all you need do to overclock it is raise the multiplier.
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Jinkazuya
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6. October 2009 @ 16:48 |
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I have read it but don't really understand the terms that well...I know that the HT uses two threads or something called rising edge and falling edge...After all, and the purpose of learning all these is that I really don't wanna get any bottleneck because of the speed difference, I think if one really want the PC runs efficiently, all the components must somewhat match each other in speed. Because if u have like a really good CPU, but the FSB of the motherboard sucks, and u don't get the real speed of the CPU you want as the damn FSB slow down the process, and even if the speed of the CPU match the FSB(assuming both having the same speed), but the if the damn RAM is slow, you won't get any faster...This is really what I wanna learn, but some of the motherboards don't really say anything about the spec of the FSB, or Hyper Transport in AMD and what they state are just the damn northbridge and southbridge, which is useless.
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6. October 2009 @ 16:56 |
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Rising and Falling edge is essentially how DDR functions - you double the speed by using both the rising and falling edges of the clock signal, that's why '400mhz' DDR2 is actually 800mhz (PC6400). Put simply, the FSB speed, neither in the Intel case, or the AMD case can 'bottleneck' the CPU. Raise the FSB and the CPU gets faster, lower it and the CPU gets slower. You can't have a high CPU speed 'held back' by a low FSB speed, the CPU simply runs directly proportional to the FSB at all times
This applies to both AMD and Intel CPUs for FSB. Hypertransport is something entirely different. I'd forget about it for the meantime as it's not really to do with what you're trying to understand.
The FSB of motherboards is not mentioned for good reason - it's unnecessary. The FSB of AMDs is always 200, and even the most basic of intel motherboards on sale today stretching as low down as the P31 all support the full range of FSBs Intel CPUs will use, from 800 to 1600 inclusive
The reason they tell you the Northbridge and Southbridge is because that is important - it indicates at reliability, and the performance / connectivity features the board is able to use.
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Jinkazuya
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6. October 2009 @ 22:21 |
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But my instructor told the whole class, and he is a computer scientist, that when you look for components you must look for the spec and see if the speed of one is compatible with another. For example, a intel CPU is 3.1Ghz, but the FSB is 2100mhz, and that will create a bottleneck, which holda back the speed of your CPU because the data transfer rate can go as fast as the speed of the FSB. That means the remaining portion speed of the CPU is unused, which becomes useless.
He also claimed that the CPU only does the logical calculation or handle a junks of tasks.
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AfterDawn Addict
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7. October 2009 @ 00:48 |
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Originally posted by Jinkazuya:
But my instructor told the whole class, and he is a computer scientist, that when you look for components you must look for the spec and see if the speed of one is compatible with another. For example, a intel CPU is 3.1Ghz, but the FSB is 2100mhz, and that will create a bottleneck, which holda back the speed of your CPU because the data transfer rate can go as fast as the speed of the FSB. That means the remaining portion speed of the CPU is unused, which becomes useless.
He also claimed that the CPU only does the logical calculation or handle a junks of tasks.
That guy is clueless...no CPU has a 2100MHZ FSB, not even in supercomputers or prototypes will you see such speeds. The I7 is about the fastest fsb around, and it runs at just 400MHZ, even with the 4x multiplier, this is just 1600MHZ...for a 3.3GHZ chip.
His logic is flawed because he seems to think that CPUs have a single serial input and a single serial output...the truth is that they have many.
Imagine a giant freeway with 4 lanes of traffic, all traveling at 3300MPH. The freeway is fed by many roads that all have 400MPH speed limits, and the freeway empties into many other roads that also have 400MPH speed limits. If you have enough onramps and offramps, then the interstate is always bumper to bumper traffic, but still running at 3300MPH down all four lanes.
I am no "computer scientist" but I still know this because I read white papers. It seems clear that your teacher does not read white papers, and is still teaching the same outdated junk that he learned in the 1970's (what he said is mostly true for processors made before the 486). I would look for another instructor if I were you.
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Jinkazuya
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7. October 2009 @ 01:38 |
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No he is sort of up-to-dated. He knows pretty well about the CPU, and he knows that the CPU works with clock tick, and pretty much about what you know. But he always emphasizes about the FSB, maybe I mistyped the FSB speed or whatsowever, and say if the speed of the FSB isn't fast enough to match the CPU, there will be bottleneck. And how fast the data could be transfered depends on the FSB and the BSB(back side bus), because this is what is used to transfer data. This is sort of what he emphasized.
That's what he told us and use the example of the water pipe. No matter how powerful the water is, if the pipe is just that small, the water will just gush out with the amount that is paramount to the amount of the water pipe. That's, because of the small water pipe, and not matter how much water is running out through the pipe, what we get is the amount of the water that the pipe could supply.
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7. October 2009 @ 08:38 |
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I can sort of imagine you might have meant to say 2000mhz, but that would be Hypertransport. As Killerbug said, there is no CPU with a 2100mhz FSB, and to add to that no intel CPU has come close (1600 highest). Now I realise why it's so difficult for you to absorb all this, you're being fed conflicting information.
If there's anything I know about computer science teachers, it's that outside whatever their particular area of expertise is, they generally have very out of date knowledge. Trouble is, most people take what they say as gospel, and thus confusion.
The FSB does not 'bottleneck' the CPU, as I explained before, it is directly related.
Quote:
No he is sort of up-to-dated. He knows pretty well about the CPU, and he knows that the CPU works with clock tick, and pretty much about what you know.
As killerbug says, that was the case back in the 1970s.
THERE IS NO BOTTLENECK FROM THE FSB OF A MOTHERBOARD.
Think about what the expression 'bottleneck' means. It means something with high performance (wide part) is slowed down by something with lower performance. It is usually applied in the context of a very fast processor being held back in games by a slow graphics card, or vice versa. For example, the game may be running at 1280x1024 resolution on high detail, which barely stresses the graphics card at all, the graphics card could produce over 200fps at twice that resolution, but the CPU is unable to render any more than 45fps, regardless of what the resolution is. THAT is a bottleneck situation.
To suggest this is true about the front side bus implies that the CPU, if the same speed as it was before, would be slowed down if you slowed the front side bus. The fact is, this is a physical impossibility. If you slow the front side bus down, the CPU clock speed comes down with it, simply due to how it's wired.
What he explains is only true of CPUs that are untied from the front side bus for speed. As far as I'm aware that only really applies to the core i5/i7, and even then that's barely true there either.
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Jinkazuya
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7. October 2009 @ 15:28 |
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- Must verify and confirm a couple things before proceeding with my question.
- Does the FSB belong to part of the motherboard? That means, when you buy a motherboard, the FSB will come with it, right?
- Does the CPU also have a FSB as well? Confusing!
Questions:
1) Quote:
To suggest this is true about the front side bus implies that the CPU, if the same speed as it was before, would be slowed down if you slowed the front side bus.
You mean this happened far way back in the older CPU? Like 10 or 20 year ago?
2) Quote:
What he explains is only true of CPUs that are untied from the front side bus for speed. As far as I'm aware that only really applies to the core i5/i7, and even then that's barely true there either.
don't really understand it, do you mean this happens to i5/i7? What do you mean by untied from the FSB?
Sorry Sammorris, and you are such a great helper, so I think I might bug you for some knowledge and hope you could understand my situation.
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Jinkazuya
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7. October 2009 @ 19:05 |
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FSB (Frontside Bus) printable version
Stands for "frontside bus." The FSB connects the computer's processor to the system memory (RAM) and other components on the motherboard. These components include the system chipset, AGP card, PCI devices, and other peripherals. Because the FSB serves as the main path from the processor to the rest of the motherboard, it is also called the "system bus."
The speed of the frontside bus is measured in Megahertz or Gigahertz, just like the processor. Most computers' processors run faster than their system buses, so the FSB speed is typically a ratio of the processor speed. For example, a Pentium 4 processor that runs at 2.4 GHz may have an FSB speed of only 400 MHz. The CPU to FSB ratio would be 6:1. A Power Mac G5, however, with a 2.0 GHz processor, has a 1.0 GHz frontside bus. Therefore, its CPU to FSB ratio is 2:1.
The smaller the ratio, the more efficiently the processor can work. Therefore, faster frontside bus speeds lead to faster overall performance. When the CPU to FSB ratio is high, the processor often has to wait for data to be sent out over the system bus before getting new data to process. For this reason, the FSB can be a bottleneck in a computer's performance. So if you are looking for a fast computer, don't just check the processor speed, but find out what the frontside bus speed is as well.
This is the info I get from the Internet. I think it is what my instructor told us in class.
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AfterDawn Addict
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7. October 2009 @ 20:21 |
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The front side bus is integral to a motherboard. It is not a physical component as such, more a set of connections that run from the CPU socket to the northbridge and are terminated at both ends. The CPU connects to the front side bus, it does not have its own.
Think of a PC as the CPU, and a website as the northbridge. The FSB is not something the PC has installed, or the webserver has installed, the FSB is the internet. In order to use the internet, the PC needs a modem, as does the website - thus, terminations.
The FSB has been used for decades, I don't know how far it goes back, but almost certainly before I was born.
Core i5s and i7s are different in how they work. For the sake of simplicity I'll leave them out of this discussion.
The latst paragraph of that page is the most important here. It is conceivable to have a 2.5Ghz CPU on various buses. A 2.5Ghz CPU with 12.5x200 is inferior to a 2.5Ghz CPU with 7.5x333. This is because the FSB communication with the system is faster with a higher speed front side bus. I think this is what you've been trying to say all along. The confusion comes from the fact that it's the CPU that decides this fact. The 'base' front side bus speed, i.e. the speed the FSB is normally set to with a given CPU is determined by the CPU you use, not the motherboard.
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