I'm confused about computer specs
July 31, 2008 11:11 AM   Subscribe

How do computer speeds vary with different core counts? Is a twin core 3000 as fast as a single core 6000? What about a quad core? Is there any point in multicore chips for home use and gaming, or does this need fancy threaded software to take advantage of it?
posted by talitha_kumi to Computers & Internet (11 answers total) 2 users marked this as a favorite
Well, I know that under Windows XP, my dual core 1.6 is much less likely to just freeze up under heavy load than my single core 2.2, probably because most apps i'm using aren't written to take advantage of multiple cores yet-- even an app that's 'not responding' will only take up 50% CPU, so I can do a force quit.
So even if you aren't using multithreaded software, if you're doing multitasking each core will have less of a load overall in terms of tasks, and your computing experience will be better.
posted by dunkadunc at 11:22 AM on July 31, 2008

You don't see a linear speedup except for perfectly parallelizable tasks, like raytracing or video/image processing. In some cases you see no improvement, like tasks that are I/O bound. But a dual core 2 GHz processor should not be thought of as being equivalent to a 4Ghz single core. That's like saying two 4-cylinder engines is the same as an 8-cylinder engine.

In general you will notice an improvement as any modern PC is almost always trying to do at least two things at once, although most of those things do not take up a lot of CPU power. If you do a lot of Photoshop or digital video work it will be a big improvement. For some games (i.e. CPU-intensive ones) it will make an improvement.

Anything more than a dual-core chip is probably a waste for most desktop users today. For servers they're great. Jeff Atwood has written a number of pieces on his blog about choosing a dual or quad core CPU for you desktop. He has some benchmark data here showing which apps benefit from a quad-core vs a dual-core.
posted by GuyZero at 11:23 AM on July 31, 2008 [1 favorite]

No its not twice as fast, but for a lot of everyday items you might notice a springiness that wasnt there with a single core. The OS will do its best to even out the load between the two cores and that can add a noticeable performance boost in some conditions. That said, modern architectures like the core 2 duo are leagues ahead of the old P4 architecture so even using one core and a lower clock speed gives quite a bit more performance. The second core probably isnt needed for most users but considering how cheap they are there's no reason to stick with single-core chips when upgrading.

More than two cores, right now, for today's typical desktop software really isnt worth it. Perhaps this will change in the future.
posted by damn dirty ape at 11:37 AM on July 31, 2008

"How do computer speeds vary with different core counts?"

They don't. An additional "core" or CPU doesn't make the computer faster. It makes it able to do more things per tick of the clock, which is a subtle difference. In some cases, an application can use additional cores to accomplish its task faster. In other cases, applications get no benefit from an extra CPU, but you could go do something else with the extra one such as watch a movie.

Generally speaking if your applications are queueing for processor time, you get some benefit from multi-core SMP. If not, you get diddly.

" Is there any point in multicore chips for home use and gaming, or does this need fancy threaded software to take advantage of it?"

Well, not necessarily fancy threaded software, but yeah, to get the best use out of an additional N CPUs, you're going to want to have either N single-threaded processes demanding processor time or a single process with N threads that are CPU-bound.

Some games can achieve small speedups by spinning certain work off to a second CPU, but there's a limit to how helpful it is. Some other common tasks get a pretty big boost out of it, like ripping and transcoding audio or video.

Beyond two CPUs, you're basically wasting your money unless you already know what you need four or eight cores for in the first place. Since you don't, you're outside that category.
posted by majick at 11:39 AM on July 31, 2008 [1 favorite]

Is a twin core 3000 as fast as a single core 6000?

Think of it like cars. A single core is one car, a dual is two. Can two cars drive twice as fast as one? No, but they can do twice as much at the same speed. CPU's are the same, although realistically you only get a 75% bonus for each extra core because there is a lot of work in managing who does what. IF, and ONLY IF the applications you run are designed to work on multiple cores. If not, they run only on one of the cores, and don't benefit at all from Multi-Core/CPU setups.
posted by blue_beetle at 12:05 PM on July 31, 2008 [1 favorite]

Once you've used a computer with two or more processors, you'll never want to go back to a single-CPU system.

The advantage of the second processor is that when one of your user jobs goes CPU bound and gets uncooperative, the GUI doesn't become jerky and unresponsive, because the other CPU is there to run it. It is soooo nice.

One fan site I used to read regularly referred to the experience as "creamy smooth response".
posted by Class Goat at 12:42 PM on July 31, 2008

For the moment processors have stopped getting faster and more cores (as well as cleverer pipelining and memory bandwidth) seems to be the preferred mechanism of throwing more transistors onto a platter (and thus charging for another generation of chips). New software that doesn't take advantage of multiple cores will suffer against competitors that do.

It's a bloody godsend for those of us who multitask a lot even if the current crop of desktop applications can't really benefit.
posted by Skorgu at 12:50 PM on July 31, 2008 [1 favorite]

Ordinary desktop applications (e.g., Microsoft Office) don't use a second core, even when multitasking. Only high-end games benefit from two cores, and even these don't use four cores yet. See this very recent item from Xbit Labs. About the only thing you can use four cores for is to run a benchmarking program that shows how much you'll benefit when real quad-core programs actually come out.
posted by KRS at 1:17 PM on July 31, 2008

Your computer will run faster with a multicore processor than with a single core. Even if all you're doing is running Microsoft Office, your computer is doing other things at the same time - rendering the interface, running antivirus, running network, printing and multimedia services. Add in playing music, browsing the web, instant messaging and so on, and multicore processors make a huge difference.

Right now, a fast dual core processor (more Mhz) is faster with most tasks (office software, gaming) than a slower quad-core processor. Quad cores are better for things like 3D rendering and video editing programs that are specifically written for multiple cores.
posted by cnc at 1:35 PM on July 31, 2008

You know how you when you think you're multitasking you're actually just thinking about one thing in an alternating way? It's just like that, only you get two brains to do it with.
posted by cellphone at 2:59 PM on July 31, 2008

Ordinary desktop applications (e.g., Microsoft Office) don't use a second core, even when multitasking.

Uh, no.

From the Xbit labs link:

"Core 2 Quad Q6600 performs very well in Excel 2007. Its advantage over the dual-core Core 2 Duo E6850 hits 63% in nominal mode and 78% after successful overclocking."

Excel will use the heck out of 2 or 4 cores. Word, not so much. I expect Access would benefit from quad core as well. Powerpoint, not so much.
posted by GuyZero at 5:48 PM on July 31, 2008

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