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AMD's archetecture difference vs Intel


amc11890
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Pentinum 4's Hyperthreading

Hyperthreading is a technology which allows the computer to be working on more than one program (called a thread) at the same time. This differs from the traditional concept of "multi-tasking" because of the following: whereas in a multi-tasking operating system (Windows, Linux, etc.) it appears that multiple programs are running at the same time, they're really not. What's happening is the computer is working on one program for 1/1,000th of a second, then it switches to another and runs it for 1/1,000th of a second, then it switches to the third, etc. So, typically only a few dozen programs are running so each of them receive a large amount of the timeslice per unit time. That makes it appear like they're all running at the same time.

What HyperThreading does is actually run more than one thread at the same time. This has an advantage over single-thread machines (ones without HyperThreading--including AMD's chips), because it is recognized that even in running the most optimized bits of code using all of the resources today's out-of-order execution engines can throw at the it, there are still unused functional units within the processor core. These unused functional units could potentially be used by a second thread. Not always, but potentially. Even if the leftover units are only able to be used 10% of the time, that's a 10% increase in performance.

HyperThreading typically doesn't add much to most code, and it usually eats some overhead to maintain (internally, the operating system must keep track of where each thread is, where it's running, how long to schedule, etc.). It's generally a wash. But, there are instances where it provides significant performance increases (70%+ increase), and other instances where it hurts performance (by 30% or more).


AMD 64's HyperTransport

HyperTransport is a bus technology. It is used to transfer data from a chip to other chips or other parts on the motherboard. HyperTransport is multi-ported, meaning that it can be operating several buses simultaneously at full bandwidth.

Generally speaking, a faster FSB speeds up everything. Faster processors only take you so far because nearly everything processor does is fed by external sources, thereby requiring the bus.

Both AMD and Intel have merits. Intel is generally accepted as the industry leader in sales volume. And historically Intel has directed the industry. However, with AMD's AMD64 technology (Athlon FX, Opteron, and X2), that has changed. Now AMD is guiding Intel (Intel implemented AMD64-compatible technology in their hybrid 32-bit/64-bit chips).

- Rick C. Hodgin


Hyperthreading is a latency hiding technique. While you may have a bunch of different programs open at once, the processor executes them one at a time. The scheduling is done very rapidly and the processor switches from task to task very quickly, so it looks like all of those programs are running at once when the processor is actually working on only one at a time. Hyperthreading allows the processor to work on two at a time, by allowing portions of the processor that would otherwise be idle to work on the second thread. That sounds good in theory, but for a number of reasons (contention caused by shared resources, and lack of software support mostly), it hasn't really worked out in practice.

Lastly, Hyperthreading is the ONLY thing that saved Prescott from making it obvious that it was a horrible CPU. If HT was not implemented in the Pentium 4, even Dell users would realize that the GHz idea is a myth and that their 3GHz Intel is slower than a 1.8 GHz AMD64 3000+. :)

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under ideal conditions it is. if two programs are running at the same time and use parts of the proc. differing from each other in the ideal way they can be executed almost simultaeneously on the core almost doubling the core. hence the p4 extreme edition with dual cores /and/ HT that can look like a 4 core proc. under ideal conditions. the problems are, as stated above, that not all software likes being executed in parallel and safeguards have to be in place to prevent one thread from changing data while another is using it.

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If your talking about the mobile parts, the Celeron M has 1mb of cache while the dothan core Pentium M has 2mb of cache.  This is the reason they can beat the higher clocked P4's in everything except for pure ram bandwidth.  The Turion 64 models differ in cache as well, there are the parts with only 512kb of L2 cache and there are the parts with 1mb of cache.

When you look at the benchies, usually the Pentium M's have less memory bandwidth than the P4's, just like the fact that the AMD proc's are starved of high memory bandwidth, but they make up for this with their low latencies because of the onboard memory controller on the processor die itself (for AMD's anyways).

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Pentium D procs are dual core, and each core has a dedicated cache of 1mb each.  The problem with the Intel design of dual cores is that each core shares the Front Side Bus, and there is a penalty in latency because of this.  AMD's design is a bit different, both have separate caches differing between the models, as 512kb and 1mb each core, but the cores can communicate directly through the crossbar interface (in other words, a mini, super-high speed bus between the caches on the proc so that the cores don't have to wait for the Front Side Bus to supply the needed information).  Hence, why I say that AMD's A64 architecture is superior for low latency  situations, like gaming.

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Personally, I didn't want to sound like an AMD fanboy, it's just that I've had such good experiences from their procs in the past many years since my old Pentium 166 with MMX tech just couldn't work with what I needed to do, though the proc itself still works, the motherboard died after eight and a half years of heavy service in which it ran win95, then win98 se, then experimented with QNX, Knoppix, Debian, then a couple months of WinXP pro with only 64mb of ram ;^)

Still, if you take proper care of the system, i.e. good ventilation around where you will have the system, and give it good maintenance then you should get a good experience out of it.  Then Pentium D 830 should give you a good experience from what I have seen playing around with some systems of some buddies of mine.  It's cheaper than the A64 dual core procs, just make sure you get a good cooling system to go with it, to keep it from throttling and lowering it's lifetime expectancy.

What I will say that favors the Intel, is that the OS will seem a bit smoother when multi-tasking.

In the end the choice is yours.  ;)

By the way AMC11890, why do you have that proc underclocked with a 6600GT in your system?  Wouldn't that lead to a worser bottleneck?

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amc11890:  I'm not up on all this tech., so I would like to know

why you are mixing pc2100 and pc2700 ram or is this a typo.

motherboards max memory speed is 2100.

I originally had 128mb 2100 mem then i added 256 2700 because it was on sale and of course it was underclocked to 2100 speeds.

So it is really like two 2100 mem modules

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  • 2 weeks later...

Personally, I didn't want to sound like an AMD fanboy, it's just that I've had such good experiences from their procs in the past many years since my old Pentium 166 with MMX tech just couldn't work with what I needed to do, though the proc itself still works, the motherboard died after eight and a half years of heavy service in which it ran win95, then win98 se, then experimented with QNX, Knoppix, Debian, then a couple months of WinXP pro with only 64mb of ram ;^)

Still, if you take proper care of the system, i.e. good ventilation around where you will have the system, and give it good maintenance then you should get a good experience out of it.  Then Pentium D 830 should give you a good experience from what I have seen playing around with some systems of some buddies of mine.  It's cheaper than the A64 dual core procs, just make sure you get a good cooling system to go with it, to keep it from throttling and lowering it's lifetime expectancy.

What I will say that favors the Intel, is that the OS will seem a bit smoother when multi-tasking.

In the end the choice is yours.  ;)

By the way AMC11890, why do you have that proc underclocked with a 6600GT in your system?  Wouldn't that lead to a worser bottleneck?

http://www.sonystyle.com/is-bin/INTERSHOP.enfinity/eCS/Store/en/-/USD/SY_BrowseCatalog-Start;sid=kKapzHDGwlOp7jMVZQGjxz_WTTobvVZIZi0=?CategoryName=cpu_rcseriesdesktops&Dept=computers

This is my computer. I think it has liquid cooling so maybe that helps?

Oh and so the pentium D is good for running a lot of programs at the same time? I'm not sure about that. When I open up task manager and I go to processes, is it supposed to have that many things running? And sometimes it says that my CPU usage was 100 percent...how's that possible? last thing...what do you mean by low latency situations?

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