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 Post subject: 2 core vs. 4 core CPU
 Post Posted: Tue Jul 29, 2008 1:50 pm 
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I know that in principle having more cores in the CPU will get things done faster, but what about when you have programs that are not particularly aware of multiple prcocessors. What then?

I was grappling with this issue the other day when I was assembling a computer for my kids. Their antique computer was getting too slow, and nothing I could do was making a big difference.

My goad was CHEAP and fast enough to get the job done. THey find a single core P4 system fast enough, so I decided to go with a system that is about 1.5 generations old.

I got a 3.4GHz Pentium D and an ASUS P5NSLI mobo, with 2G ram.

But how does a 3.4GHz Pentium D compare to a 2GHz quad core new CPU compare when using essentially single threaded programs? Also, not a LOT of multitasking, but I assume that running their AIM in the background was one of the culprits that was bringing their old (antique actually, but comparatively FAST P3 system to its knees).

I wonder what Core-2 processor is the speed equivalent of a 3.4 or 3.8GHz Pentium D in an otherwise similar system (same speed FSB, RAM)?

-Tony


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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Tue Jul 29, 2008 4:26 pm 
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Hmm I'm not sure if what speed of C2D relates to an old pentium but I had to consider this as well before buying my 630 (Q6600 vs E8500 for same price).

It is true that at the moment there are very few programs out there designed and optimised for multi-core use. Thus, it is usually the case that in everyday use you are using only 1 core out of your 2/4 meaning that a faster 2-core will outperform a slower quad-core (or as in your example that a 3.4GHz pentium would outperform a 2GHz C2D). Even for newer programs which are optimised for multi-core use, many of these are optimised for 2 cores rather than 4 (as these are still much more common). There are exceptions to this, eg professional video encoding etc, but currently I'd say (and so I chose) that 2 fast cores are better than 4 slower ones, for the simple reason that, in general use (and particularly gaming), it is very uncommon that you'll actually be using all 4 at any given time.

However, I think the final thing to consider is future-proofing your system. It now looks inevitable that multi-core computing is the way of (at least the near) future, with Intel talking about 8 and even 16 or more cores in their upcoming Nehalem processor. Thus, as time goes by, more and more software will be optimised to run in multicore environments and these slower quad-cores will retake the lead. I still went with dual-core myself as I plan to upgrade my processor before it's obsoleted in this way; if however you are planning to stick with one processor for a long time, then it might well be worth going quad - it's slower for now, but in 2 or 3 years that could all change...

sorry for the really long post! just my 2 cents...

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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Tue Jul 29, 2008 4:44 pm 
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Even if a program isn't multiple processor aware or optimized that doesn't necessarily mean it won't use all the cores it just won't be as efficient at it and that doesn't mean the OS won't be able to divvy up other tasks to other cores. You also need to consider that newer processor can do more work per clock cycle so that also makes them more efficient which translates into speed.

You can't really compare processors like the Pentium D and newer Quad cores based on chip speed even if the rest of the system is the same. Newer chips have better and larger internal memory cache and functions such as SSE4 that make processing more efficient. Roughly speaking a new Quad 6600 should be about 181% faster than the Pentium D overall.

Probably not what you are looking for but I hope it helps a bit and I'm sure there will be a lot of different views on this topic. ;)

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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Tue Jul 29, 2008 5:34 pm 
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wintergreen wrote:
...sorry for the really long post! just my 2 cents...



No, some ideas take more than a few words to express.

You confirmed some of my general impressions about the state of the software out there, I.E. much software is not going to use more than 1 core at a time. So multiple cores will help run multiple applications at the same time, but not help any one application run faster by itself.

I do not know how much more efficient the Core platform is than the Pentium platform, but the Core platform IS more efficient. for a 2GHz quad core, the efficiency would need to be 41% greater for the Core to compensate for the clock speed. It might well not be faster than a 3.4Ghz CPU.

But for a 3GHz dual Core CPU, it would need to be 12% more efficient than the Pentium CPU. This might well be faster than a Pentium D on a per-clock cycle basis. My general impression is the Core is 30% more efficent than the Pentium platform.

All else being equal (i.e. FSB and RAM speeds, which they are NOT), My impression is that a Core CPU would need to be running at about 2.3GHz to match a 3.4GHz Pentium D CPU.

So, in my attempt to get a CHEAP system for current single thread applications, I think I am going to be reasonably OK going with a 3.4-3.8Ghz Pentium D working at an 800MHz FSB with 667MHz RAM on something like an ASUS P5NSLI mobo. When the software reaches the point that even more is necessary, then it will be time to get something that is quite up to date.

-Tony


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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Wed Aug 06, 2008 4:24 pm 
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Interesting article here: http://www.guru3d.com/article/cpu-scaling-in-games-with-quad-core-processors/ about dual- vs quad-core scaling in games - turns out that even a $60 processor doesn't run much worse than QX9770 in a lot of games! Particularly at high resolutions when your GPU becomes the limiting factor...

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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Wed Aug 06, 2008 6:02 pm 
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Also, as I understand it, quad core processors are only supported in Vista (and later), so if you have long-term plans to stay with XP, it won't do any good to buy a quad core system.

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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Wed Aug 06, 2008 6:32 pm 
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gdonner wrote:
Also, as I understand it, quad core processors are only supported in Vista (and later), so if you have long-term plans to stay with XP, it won't do any good to buy a quad core system.


What the heck? Where did you get that one gdonner?

I have a quad-core and XP and it works just fine. When I'm not gaming I run Prime95, one instance on each core. Works just fine. And when I go into the Task Manager I can see 4 CPU graphs.

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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Wed Aug 06, 2008 7:05 pm 
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Maybe?

:lol: :D

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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Thu Aug 07, 2008 12:18 am 
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No, I'm not into wacky weed--I got that tidbit from my I.S. guy where I work; I'll ask him for references, since I'm having a hard time finding official data to support either side. :geek:

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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Thu Aug 07, 2008 1:33 pm 
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Drange wrote:
You can't really compare processors like the Pentium D and newer Quad cores based on chip speed even if the rest of the system is the same. Newer chips have better and larger internal memory cache and functions such as SSE4 that make processing more efficient. Roughly speaking a new Quad 6600 should be about 181% faster than the Pentium D overall.

Probably not what you are looking for but I hope it helps a bit and I'm sure there will be a lot of different views on this topic. ;)


Actually, that IS what I was looking for. I was interested in not just overall speed of entire platform, (including the higher speed RAM, etc), but I was interested in the speed of the CPU itself (instructions completed per clock cycle, including the effectiveness of the L1 and L2 internal caches).

After looking at some speed results, I think my 130% guess was low. I think I am seeing something approximating your 181% advantage. This means that my C2D E8400 running at 3.0GHz is approximately the same as a Pentium class running at 5.4GHz. However I think that this is the upper limit of the speed advantage.

-Tony


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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Thu Aug 07, 2008 3:59 pm 
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As you guys suspected, the info I quoted from my I.S. guy was wrong (sorry about that!)--here's what I got back from him when I asked for references to his original statement:

"I did some research, and I found that I wasn't completely right regarding Windows XP and multiple processors. Windows XP is limited by processor sockets, not processor cores. Windows XP Home supports only one socket, but it can have multiple cores up to at least a quad core. Windows XP Pro can support two sockets with multiple cores in each processor up to eight cores.

I don't have a specific, authoritative web site for reference at this time. I found a lot of people commenting on the issue, but I wouldn't consider them authoritative."

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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Thu Aug 07, 2008 4:36 pm 
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Can you run it will give you a performance rating based on a Pentium 4.

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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Thu Aug 07, 2008 11:20 pm 
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Great website--thanks! Added to the Collective "Links" page.

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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Fri Aug 08, 2008 1:25 am 
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I emailed tech support at SRL about that performance rating awhile back, and he said that because the Gigahertz Wars were over, that Intel and AMD had to differentiate their CPUs, and so they went to a performance basis. The Pentium 4 2.66 GHz being the baseline. So something that is performance rated at 4.0 is 4 times faster (or 4 times better in performance) than a P4 2.66 GHz.


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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Fri Aug 08, 2008 4:08 am 
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Interesting performance ratings.

On my Pentium D 3.4, 800 FSB, 4G L2. I got a performance rating of 6.12GHz. Not much of a drop below the rated performance of your quad core 2.4GHz which got a rating of 6.24!!??

I suppose that this is a per-cpu rating? It seems as if the rating is a little low for your C2 quad or a little too high for this Pentium D 3.4?

-Tony


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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Fri Aug 08, 2008 4:26 am 
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And my other machine, an AMD Athlon 64 x2 4800+ (2.5 GHz) got a performance rating of 7.20. So I'm not sure what to make of that rating, that's why I emailed SRL support about it.

All I know is I get good frame rates in Crysis, lol.


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 Post subject: Re: 2 core vs. 4 core CPU
 Post Posted: Fri Aug 08, 2008 5:15 pm 
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Using "can you run it" on my 630i with an E8400 Dual 3GHz C2D, I got a CPU benchmark of 9.00GHz. I still don't see how they got the number for your quad processor....

-Tony


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