re Processor Speeds vs number of Cores

[BigEvil]

I've searched all over but found nothing but conflicting opinions and reports regarding this so I figured I'd post the question here and see what you guys say.

I'm gonna be buying a new Mac Pro in the not too distant future but I can't seem to find out where you're better spending your money with regards to processors & cores. For example, is one better off getting less cores but higher processing power OR more cores with slower processor speeds. Then additionally the processor class obviously comes into play and screws things up even more but basically I just want to know are you better off going with a single 3.2GHZ Quad Core or 3.33 6 Core over two 2.4 GHZ quad cores... etc...

I'm just so confused as to which will be the best suited for Pro Tools HD.

Any help is greatly appreciated

[sunburst79]

I beleive in cores over clock speed.

[chrisdee]

Originally Posted by sunburst79

I beleive in cores over clock speed.

+1. Less is not 'moore' when it comes to processors.

Infact, since the processor clock speed has not increased much the last few years, but the number of cores has the term moores law should be renamed to cores law

[Barry Johns]

It's opposite for DAW's, it's clock over cores. Most apps are still not written for multiple cores, that's why a 6 core out performs an 8 core. Lots of threads about this.

[sunburst79]

Originally Posted by Barry Johns

It's opposite for DAW's, it's clock over cores. Most apps are still not written for multiple cores, that's why a 6 core out performs an 8 core. Lots of threads about this.

We running the same app? PT has been multithreaded since 7.0.

[chrisdee]

Originally Posted by Barry Johns

It's opposite for DAW's, it's clock over cores. Most apps are still not written for multiple cores, that's why a 6 core out performs an 8 core. Lots of threads about this.

[BigEvil]

this thread is a wonderful example so far. two of you say cores, two of us say clock. I wish there was a actual finite answer or proof supporting either claim. hmmmm.....

[drenkrom]

Originally Posted by sunburst79

We running the same app? PT has been multithreaded since 7.0.

Multithreading and multiple-core support are two distinct things. Multithreading is meant to maximize the utilisation of a single core. Each core in a multiple-core system supports multithreading, but multithreading support does not imply multiple-core support. My head hurts just typing that.

The opinions are neatly divided but the thing is they're all right. Some of the time. Some software uses multiple cores a lot more efficiently. For example, Adobe CS5 has better support for multiple cores than Final Cut Pro. A CS5 system will take more benefit from a multi-core system than FCP will, while both applications will benefit pretty equally from higher clock speeds.

For PT, I have no idea. Seeing as it's built on some pretty old foundations, I'd wager clock speed would be more determining, but it's a shot in the dark, really.

In the future, the number of cores will probably win out since it's that aspect CPU developers are pushing.

IHTH

[O.G. Killa]

I think it all boils down to how fast the computer can compute... Would 6cores at 3.3GHz be able to do more FLOPS (Floating-point Operations Per Second) or would 8 cores running at 2.4GHz?

It's not an easy question to answer and the design of the chips have some effect. If all six cores are on one chip, the speed between them is faster than two quad-core chips since you only have 4 processors on each chip and then you have to bridge between them to get 8.

The design of the Cache for the processors effects the speed of the computer. As well as the bus speed of the RAM.

So there is no one definitive reason why one is faster than the other, but lots of little ones that can add up.

Looking at a 3.33GHz 6Core Westmere Mac. The RAM runs at 1333MHz and it is ONE chip with 6 processors on it. It also has 12 MB of cache shared between all 6 processors.

If you look at the 2.4GHz 8Core Westmere Mac. The RAM runs at 1066MHz, NOT 1333MHz. And the L3 cache is 12MB PER CHIP. Which means if the processors need to share the cache, it can only do so at extremely fast speeds within 4 processors, if one chip has to hand off data to the second chip to continue processing, it has to go OUTSIDE it's L3 cache to do so because the 12MB Cache is per Quadcore chip, not all 8 processors. This will also slow the computer down slightly.

So you add up the facts...

The 8 core is 2.4GHz instead of 3.33GHz
The 8 core's RAM runs at a slightly slower speed
The 8 core's L3 cache is NOT shared by all 8 processors directly

These three very little details can (and pretty much does) mean that the 6 core will be faster than the 8 core. But not by much.

The one benefit the 8 core has over the 6core right now is RAM. Even though the RAM is slower, it has EIGHT slots for RAM, while the 6core only has FOUR. So you can put twice as much RAM in the 8core. If you need a lot of RAM to do what you do (Zimmer-esque orchestral mockups, etc) then the 8 core might be a better choice since you can put a lot more RAM in it.

AND the 8 core is about $200 cheaper than the 6Core... Which could go to more RAM, a second (or third) LCD Display, a Virtual Instrument or Plugin... etc...

[drenkrom]

Derek just out-geeked me massively. Spot on analysis.