Part 2: How Many CPU Cores Do You Need?

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marraco

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[citation][nom]Edgar the Wise[/nom]Just a bit of terminology: "linear" should mean a function x -> cx (that is, twice the performance with twice as many cores, etc.) The correct mathematical term for a function x -> b + cx is "affine function", a very different concept in this context.Also, I can't understand why 7-zip couldn't have a go -- it has long been optimized for multiple cores unlike WinZip and WinRAR (previous test), its compression algorithm is superior to RAR and ZIP, and it's free software.This is a very useful article nevertheless, so thanks a lot![/citation]

You are right, but they meant linear Variation (derivative is the same, independently of b)
 

ossie

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"Core 2 Quad Q6600's split cache"
Q6600 is practically a 2 way dual-core (2xE6600) not a "split cache" CPU, as the two independent DC-CPUs are communicating through the FSB (even if they share the same housing).
Ever heard of SMP cache coherency? It has been an issue since the first SMP system...

This clearly pictures why TH mostly sucks. A real scientist analyzes the data and (hopefully) gets a profound understanding of the involved phenomena.
An assistant collects data in a spreadsheet, draws nice graphs, eventually types a few pages of text, and, mostly, that's it.
 

randomizer

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[citation][nom]apache_lives[/nom]again with the prehistoric benchmarks - styled in 1999, not for 2009if i look down at my task bar as i write this i have 2 tv shows recording, msn messenger, torrents, antivirus, video playing, and god knows whatever else i am running IN A NORMAL SYSTEM NOT A CLEAN FRESH INSTALLi also love playing gta iv online which in its self loads up all the coresTHERE IS NO WAY A DUAL CORE IS CLOSE TO A QUAD IN THE REAL WORLD AS I CAME FROM AN E6600 TO THIS Q6600[/citation]
I do one thing at a time, or two if I'm really multi-tasking. I must be an old young person.
 
[citation][nom]rdawise[/nom]Hmmm...by your logic, quads will soon become obsolete. There is no such thing as "future proof". Think about, Intel and AMD both will probably have switched sockets in the coming year or two so your quad core will be outmoded.Point:Buy the best that suits your needs and hope that it includes a suitable upgrade path.[/citation]

Yup sure it will be obsolete - not saying it wont be and even then i wont be ranting about my crappy quad because i own it and think i know best when there are better things out there - thats what trolls do ;)

[citation][nom]randomizer[/nom]I do one thing at a time, or two if I'm really multi-tasking. I must be an old young person.[/citation]

yet in the background there are atleast 5 different things running on any pc - take a look at task manager at how many threads/apps are actually running and divide that by the ammount of cores you have and see how your figure stacks up against a quad or an 8 threaded i7

what were forgetting here is that while a quad doesn't show up here as notably "faster", if you were running these benchmarks here ASWELL as using the system normally OR playing a game or whatever you WILL see the difference as the free cores will actually see use

owners of an i7 or users will know what i am talking about where no matter the load the system is still very responsive and "fresh", as for the rest of you that have never seen or used an i7 have no idea what you are missing out on and have no right to vote against or speak against it - use an i7 before saying that extra core and threads are not usefull or make any difference.
 
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yeah performance/OC/€ does very matters

thank AMD for 720BE
( +water Tt vb5001)
 
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I'm very sad to see that there was no Photoshop benchmark included. By your previous cpu tests CS3 was much faster running on dual cores and there have been some to my knowledge unresolved questions as to whether CS4 can now utilize more than two cores.
 

randomizer

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[citation][nom]apache_lives[/nom]yet in the background there are atleast 5 different things running on any pc - take a look at task manager at how many threads/apps are actually running and divide that by the ammount of cores you have and see how your figure stacks up against a quad or an 8 threaded i7[/citation]
Most of those processes sit idle or close to idle for the majority of the time they are running.

[citation][nom]apache_lives[/nom]owners of an i7 or users will know what i am talking about where no matter the load the system is still very responsive and "fresh", as for the rest of you that have never seen or used an i7 have no idea what you are missing out on and have no right to vote against or speak against it - use an i7 before saying that extra core and threads are not usefull or make any difference.[/citation]
I own an i7. My system responsive way earlier than my old system was after booting, but I also have an extra 2GB of RAM, a new and much faster HDD and a different (and newly installed) OS. Once my old system had finished prefetching everything (which took forever) it was nearly as responsive as this one.

Of course if I throw in some video encoding while gaming there's some slowdown, but only in the encoding, and this exists to a lesser extent with i7 as well. I don't regularly do that though due to the fact that the system produces far too much heat with that kind of load.
 

aihyah

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most of the time dual core will do. its when you get used to that and try something more, maybe unzipping a large file, encoding video, burning stuff while playing a video etc...its nice to have more than 2 cores to keep the system from ever hickuping.
 

aihyah

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most of the time dual core will do. its when you get used to that and try something more, maybe unzipping a large file, encoding video, burning stuff while playing a video etc...its nice to have more than 2 cores to keep the system from ever hickuping.
 

aihyah

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most of the time dual core will do. its when you get used to that and try something more, maybe unzipping a large file, encoding video, burning stuff while playing a video etc...its nice to have more than 2 cores to keep the system from ever hickuping.
 
Some people want to hoist a massive edong. That's fine, and they may well expect (and be able) to pay through the nose for it. Some, however, focus on frugality. While they would do well to anticipate future needs as well, they are more likely to take a minimalist approach.
 

jeffq

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I'm an old Unix multiprocessor guy, and I'm intrigued to see how PC users are rediscovering the ins and outs of MP systems. jtt283's point about AVG's speed setting is important for these tests, and if Don's test info said anything about this setting, I missed it.

I believe the default setting for background scans is "Automatic", about which AVG's relevant FAQ is rather vague. But if you set it to "Slow scan", it should confine AVG to a single thread and give the host CPU some breathing space to run other threads (like system and utility threads). Other applications may have similar settings.

A separate issue is whether or not you can confine threads to a single CPU. The Unix systems I've dealt with can do this, but I don't know if Windows-whatever has this capability (or if it does, what arcane combination of configuration elements one must invoke to use it). If you're gaming, I'd assume that you'd be more than happy to tell the OS to force all possible threads except those handling your game to run on a single CPU. If you can do this, you might find that you won't notice much (if any) degradation while playing, since your game would have all other CPUs to itself.

MP load-balancing is a non-trivial discipline. Savvy power users should be able to do a better job tuning their multi-core systems empirically for their specific mix of tasks -- if they have the tools to do it -- than Intel, AMD, and Microsoft, who probably have to focus on broader use cases.
 
In Windows, it is done in Task Manager by setting the "Affinity" of a particular process, specifying the cores it may use, or allowing it to use them all (the default). IIRC, this setting used to "stick" between executions of the same program, but I know in the Windows 7 RC, it does not. I believe it should be added to some Advanced Properties page of every executable file on the system, applying to that file and to any other processes it starts. I also wouldn't mind seeing a default setting on some kind of System Properties page to default to a certain number of cores if not overridden for a given executable; there may be a registry hack for some of these, but I haven't found it (nor taken a lot of time to look) yet.
 

jeffq

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Setting a property for an executable might be an logical Windows-ish way to do things, but it's not really scalable even for basic Windows systems. (How many thousands of executable components are there in a typical system?)

What's really needed is an overall OS-based (not file-based) configurable load-balancing manager that can reserve a CPU for a small subset of executables, or force all other tasks besides a subset to use one or more specific CPUs. I wouldn't be surprised if such a thing doesn't exist yet for an OS that rarely if ever had to run across more than 2 CPUs until recently.
 

norfindel

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I see good framerates with dual core there. Better to buy a good video board with a dual core, than a crappy video board in a quad core. You should do an article comparing that.
 

cisco

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Just built a 720 X3 PC for my nephew and it's a great processor for the money. Really a nice processor for a good budget gaming rig.
 
I have been testing out a 720BE (possibly undervolted/underclocked) as a lower-power alternative to my Q9450. So far, I do not feel compelled to return to the Q9450. I need to wipe the Q9450 and put a fresh Win7 RC on it, to confirm whether or not my P35 mobo is ill.
 

nelmr

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Tom's should add Anno 1404 to the gaming benchmarks. It looks like that game favors 4 cores:

http://www.pcgameshardware.de/...-Anno-1404/CPU/Test/
 
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It would have been nice to see some up/down loading put into the multi-task barrel. IO puts a lot of interrupt stress on the CPU and is a common multi-tasked scenario.
 
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I'm interested in learning what impact DirectX 11 will have on the effectiveness of 3+ cores, once game engines have been changed to take advantage of it. Right now, games are usually bottlenecked by a single DirectX rendering thread. This is why a second thread (and core) can help, but only up to a point, and a third core makes hardly any difference. DirectX 11 has many provisions for allowing more effective use of mutiple cores. But how many will be really useful in practice until the game is limited by something else, such as required rendering sequencing or the graphics card. I happen to be in an unusual situation where I'm preparing to upgrade, but my existing motherboard will support at best a Phenom X4 (officially) or a Phenom II X3 (unofficially, but it usually works)--not a Phenom II X4. To get to a more modern four core CPU I'd have to pay for a new motherboard, potentially requiring new memory and a new cooler if I switch to Intel. The incremental cost of a higher end fourth core is therefore quite large, leaving less for the graphics card and other extras. So which path do I take? Will the fourth core matter that much or not for the typical future game? I've been waiting a while already, so I'll need to decide before the next gen DX11 games hit the streets.
 
[citation][nom]KyleSTL[/nom]Why no power consumption testing? I was a little curious what disabling cores in the OS would do to power consumption under load. A little let down, but otherwise good article. It's good to see a scaling article at least yearly since people refer to the dual/quad debate so often and often the tests that were run within article that are referenced are out of date and irrelavent.[/citation]

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My PC when i play GRID do the scan full for the 2 HDD
 

jawshoeaw

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Not everyone runs a virus scan. Never had a virus - just did a check with some online scanners for the fun of it. No spyware, no viruses. Maybe with a quad core I'll be willing to install AVG.
 

ilikegirls

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they talk about disableing the cores using the OS. now i have an i7 920 at 3.33 and i want to see if disableing 2 cores makes a difference in some games or programs so how do i disable 2 cores ? or even HT ?
 
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