Pentium 4 pros and cons

[Arcadian]

We all know a good amount of what will be included in the Pentium 4 architecture. Intel has made a great amount of information available about this. However, one thing we do not have is any reliable performance numbers. So, I wanted to get some hard core speculation regarding the Pentium 4. This thread has really died down this past week, so I wanted to recessitate it a little. Come on and help me out.

What I'm looking for are people's opinions on what aspects of the Pentium 4 will likely be fairly positive or what will be fairly negative. What do you think has been overrated to the point of marketing hype, and what do you think needs to be discussed more? Do you think the Pentium 4 will surprise everybody, or dissapoint. I welcome opinions, but would like it more if you could keep this technical, so we can respond to ideas.

Here are some aspects that could warrent discussion:

- 400MHz Front Side Bus
- Double Pumped Execution Units
- Lack of Dual Processing at Launch
- More than Double the Heat of Pentium III
- Rambus Memory
- High Bandwidth Caches
- 20-stage Pipeline / Branch Misprediction
- High Clock Frequencies
- Higher Clock Frequencies in the Future
- Excellent Branch Predictor
- Small L1 Cache
- Trace Cache
- Large # of Instructions in Flight
- New PC Specification / Large Heat Sinks
- Low Expectations (on Websites)
- Rumors on the Web
- i850 Delays
- Price Issues
- Much More!

Wow... this is a lot to talk about. Hopefully, we get some good discussions going.

[gamigin]

Rambus mem's? what for? they're expensive and are they really that good?
Doubled heat aye... gotta get a hell of a fan i guess... or just stick with AMD

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- GamigiN

[jtshaw]

I know a lot of people have already counted the P4 out. There has been lots of speculation that it isn't going to be as fast as the Athlon or even the PIII on a Mhz. to Mhz. basis and people seam to have fun talking about how crappy of a product it is. This all might be true but it could just as easily be wrong.
There are a few things I see in the P4 that lead me to believe Intel understands what new processors need. One is the 400 Mhz. (or 100Mhz. "Quad Bumped") bus. AMD seamed to catch on a little earlier with the Duron and the Athlon that bus speed is an important factor (maybe a lesson they learned back when the PII beat them to 100Mhz. and won the proformance title). Intel took a nice jump from 133mhz. all the way to 400mhz. Another interesting thing I heard is that Intel is working on a DDR chipset for the P4 and is trying to figure out a way to break the contract with Rambus.
RDRAM is definitly something to talk about with the P4 because even if Intel does create a DDR chipset we won't see it for a while. From what I gather, in terms of the PIII, RDRAM had no real benifit because the bus couldn't match the high ram speed. It is possible that with the P4 RDRAM could actually cause proformance increase because of it's added bus bandwidth. Troubles with RDRAM aren't looking to go away and it will still probably be rather expensive and hard to get a hold of.
Another major feature of the P4 I think is worth discussing is the 20-stage pipeline with "Branch Misprediction". This seams to be the heart of the P4's high clock speeds but it could also be the reason why P4 doesn't appear to be all that much better then the Athlon or PIII at this time. It could be software needs to be optimized to take full advantage of this. The longer pipeline also means if bad information gets into the pipeline it will take longer to flush it out...
The double pumped executions units are another feature that I think could be excellent for proformance if code is properly optimized to take advantage of it.
One thing many people on these forums, as well as elsewhere, are going to gripe about is the price of the P4. It will be expensive comparitive to AMD parts. Intel has a pricing stratagy that involves supply and demand. Intel hasn't needed to lower the price of there processors as much as AMD has because they are still selling more of them. AMD is making money for the first time ever but they are still making far less then Intel. Businesses are still more likely to go with Intel parts because they have been buying them for years. I am not saying this is right but for now it is the way things are.
I have been blabbing on for too long already...to end this for now, I think that the P4 has some features which look like they could be really great for proformance. They are also plenty of questions in my mind about the ability of the P4 to really proform. I can't wait to see it come out so we can run it to the ground and see just how well it runs.


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My computer said "WindowsME/2000 or better" so I installed Linux.

[LiquidGoop]

One thing that you overlooked, so I just had to bring it up, was the fact that the p4 will be TWICE as big as the p3. This means taht intel will only be able to produce half the amount of cpus on the same wafer. However, intel has said that supply will not be a problem. I think everyone remembers the p3 1.13Ghz.. err.. incident. I'm not tryingto bash intel, the p4has alot going for it, especially the 400Mhz bus. The 20-stage pipeline might hurt it somewhat,that lost ground might easily be made up by the excellent branch predicotr. Hard to tell at this point, looks like some pros and cons toeven out, coincidently the title of teh topic.. The small L1 cache looks like a bad decision, IMO. Seeing the high clockspeeds, you'd think that it would have more l1 cache.

Anybody have any mustang specswecould compare the p4 to? Wear anasbestos coated jacket tho, we know how things can heat up in here

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"A P2 450 and a Savage should be enough for anybody"
-Mike, October 2000

[Phoenix]

I'm interested to see how the 400MHz FSB helps mempry performance as I have heard arguments from both sides. I don't really think that a lack of dual processing at launch will hurt them too much, as long as AMD doesn't have a good dual setup that performs better than the Intel line. The only large market for dual, or larger, setups are servers for business, which Intel will still have control over, even if AMD does come out with something better. I'm wondering if the small cache will be a good idea, even if the cache is faster. Would a small amount of cache have a bigger hit on performace if it was used in a server? If so, maybe this is why they haven't come up with dual support yet. Price could hurt it, and low expectation could really help the P4 if it turns out good, the public loves a good surprise.

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When asked how World War III would be fought, Einstein replied that he didn't know. But he knew how World War IV would be fought: With sticks and stones!

[Arcadian]

Originally posted by Phoenix:
I'm interested to see how the 400MHz FSB helps mempry performance as I have heard arguments from both sides. I don't really think that a lack of dual processing at launch will hurt them too much, as long as AMD doesn't have a good dual setup that performs better than the Intel line. The only large market for dual, or larger, setups are servers for business, which Intel will still have control over, even if AMD does come out with something better. I'm wondering if the small cache will be a good idea, even if the cache is faster. Would a small amount of cache have a bigger hit on performace if it was used in a server? If so, maybe this is why they haven't come up with dual support yet. Price could hurt it, and low expectation could really help the P4 if it turns out good, the public loves a good surprise.

I may have some insight regarding your cache size concerns. From what I have heard (from various sources ) is that the 8KB d-cache is sized to allow for scalability into >2.0GHz ranges. This will not apply at first, but remember that Intel would like the design to be around for approximately 5 years like the P6 architecture.

In terms of servers, there will be a version of the Pentium 4 called Foster (which will probably be named Pentium 4 Xeon). Like the Pentium III Xeon, there will probably be small cache versions and large cache versions, the latter of which will be used in departmental/enterprise servers. The large cache will not be L2, but rather L3, and will probably come in sizes ranging from 1MB to 3MB. From what I know, this product will come later next year, so as to not conflict with the 900MHz Pentium III Xeon (with 1MB or 2MB of cache) due out in a couple of months.

The server market should really be heating up this next year between Sun's Ultrasparc III and Intel's Pentium 4 Xeon. Personally, I think the Pentium 4 Xeon (still not certain on this name?) will kick the pants off Ultrasparc III .

[jtshaw]

A quick comment about the Pentium 4 Foster/Xeon vs. the UltraSparcIII. If The P4 Xeon is kin to the P4 like the P3 Xeon is to the P3 then it will probably crush the ultraSparcIII on many levels...you ever tried to get upgraded hardware for a sparc station? PAIN IN THE BUTT!

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My computer said "WindowsME/2000 or better" so I installed Linux.

[-= HaX0r =-]

Just go with AMD from now on, Intel is losing their strong hold on the market.

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PIII-800@ 1002mhz
Asus CULS2 mobo
512mb Micron ram
46.1gig ata-100 IBM hdd
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Ricoh CD-RW 6/4/32
8x Toshiba DVD-Rom
Linksys LNE100TX nic card
Running WinMe,Win2k,and Whislter

[Phoenix]

Originally posted by Arcadian:
I may have some insight regarding your cache size concerns. From what I have heard (from various sources ) is that the 8KB d-cache is sized to allow for scalability into >2.0GHz ranges. This will not apply at first, but remember that Intel would like the design to be around for approximately 5 years like the P6 architecture.

In terms of servers, there will be a version of the Pentium 4 called Foster (which will probably be named Pentium 4 Xeon). Like the Pentium III Xeon, there will probably be small cache versions and large cache versions, the latter of which will be used in departmental/enterprise servers. The large cache will not be L2, but rather L3, and will probably come in sizes ranging from 1MB to 3MB. From what I know, this product will come later next year, so as to not conflict with the 900MHz Pentium III Xeon (with 1MB or 2MB of cache) due out in a couple of months.

The server market should really be heating up this next year between Sun's Ultrasparc III and Intel's Pentium 4 Xeon. Personally, I think the Pentium 4 Xeon (still not certain on this name?) will kick the pants off Ultrasparc III .

Thanks for the info. Arcadian. I have been playing some Sun Sparc's lately, at the University I attend some of the member of the Linux User's Group setup a Beowulf cluster of Sun Sparc 5's, not the fastest CPU's in the world, but they were free

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When asked how World War III would be fought, Einstein replied that he didn't know. But he knew how World War IV would be fought: With sticks and stones!

[Flip]

The Pentium 4
New Architechure?
New Instrucion Sets?
Quad-pumped 100MHz FSB?

Lets think about this whole thing logically, so we can really see if this new chip will do more for us than a Pentium 3.

First of all, the p4 implements hyper-pipelining, which means that it has a 20 stage pipeline, which the p3 only has a 10 stage pipeline. With this hyper-pipeline there is a possibility for higher clock frequencies, but also with this deeper pipe comes more room for error. Lets think: If the p3 has 10 stages, that means that the ALU is predicting instructions and executing them 20 steps down the line, that means that in simple terms, if there were only two instructions, 1 and 0, there would 1024 different paths down that pipe, and the algorithums job is to try very hard to speculate which path out of 1024 to take. Now, that being said, if the p4 has 20 stages, do the math for two instructions, and that would over 1.04 million paths, so now these new and improved algorithms can now predict with the same accuracy which path to take out of 1.04 million? I think not, no matter how many super-genius's they had working on the new algorithms. Not to say that this new 20 stage pipeline is all that bad, Intel has also implemented Advanced Dynamic Execution can keep up to 126 instructions in flight, which helps keep the mis-predictions to a minimum. Another way that Intel intends to solve this problem is the variation of L1 cache called trace cache, which stores decoded x86 instructions in the flow that they are to be processed. Also with the 256K of Advanced Transfer Cache running at full speed with a 256 bit path to the double clocked ALU's this processor will not have much time to rest, and in turn will generate MUCH MORE heat!
About the SSE2, of course they had to throw some new instruction sets in, but as of right now, there is no such software that is coded to take advantage of these new instruction sets, so we will talk about how good they are when we have a chance to see them in action. And to conclude, there is no clear definition as to which is better(p3 v. p4), all we can do now is just sit back, relax, wait until they are released, and let the benchmarks be the judge.

Flip
(as in the chip)

[Arcadian]

This is for Flip.

I'm sorry, but you have the wrong idea of how a pipeline works. If I weren't so busy right now, I'd explain it to you. Maybe I'll have time later. I just wanted to clear that up, because your relation of a pipeline to branch prediction is not correct. Thanks for the response, though... I'll try to get back to you later.

[Arcadian]

Originally posted by -= HaX0r =-:
Just go with AMD from now on, Intel is losing their strong hold on the market.

HaX0r, the idea here is to get some discussion going, not to close the argument with a one line opinion. If you think AMD has a stronger hold on the market, can you please explain why?

[jtshaw]

Surprisingly Intel isn't really lossing anything. They are still making more money and I believe even selling more chips then AMD. Not to say AMD chips are crap, they aren't, but Intel is still the proven solution for businesses as has been stated time and time again on these forums. I would hardly say Intel's stance is in trouble at this time.

Originally posted by -= HaX0r =-:
Just go with AMD from now on, Intel is losing their strong hold on the market.

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My computer said "WindowsME/2000 or better" so I installed Linux.

[This message has been edited by jtshaw (edited November 02, 2000).]

[Flip]

Arcadian
Sorry, I didn't mean to sound like an idiot, I wasn't sure completely how it works, I just inferred a lot from what I had read, if you could point me to a good article explaining the 20 stage pipeline, it would be much appcreciated, or even better, if you gave me an explaination, I'd be very greatful!

Flip

p.s. no hard feelings? I'm pretty new at the deep down technical interworkings of the microchip.

[zombor]

hmmmm...i cant remember offhand how big the PIII pipeline is, but isnt 20 more than double what the p3 had? If this is true, it would take the proc twice as long to process n instruction, but the clock speed would be able to be doubled, right? Then, if the chips will debue at 1.4 and 1.5 Ghz, the "rawprocessing power" would be an effective 700-800Mhz p3(assumming there arent any p4 optimized instructions being used). If im wrong tell me, cause at this point, in seriously doubting this chip as a contender for games and shuch.

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Compaq Armada E500
650MHz PIII 128MB RAM
8MB ATI rage mobility
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