[Eden Aurora]

If i'm looking to get the fastest computer possible, below are my options:
6-core Mac Pro at 3.33GHz
8-core system at 2.4GHz
12-core system at up to 2.93GHz

Wouldn't the 6-core at 3.33ghz run faster than an 8 core at 2.4ghz for 99.9% of our applications because 99.9% of our applications can't use all the cores?

OR, since the Mac Pro features Turbo Boost, and Turbo Boost increases the speed of the active ones, up to 3.33GHz on a 12-core Mac Pro, and up to 3.6GHz on a 6-core system.....then both the 8 & 12 core systems will always run faster than the 6 core?

[Don Pickett]

There are too many variables to simply answer that question. It depends on whether the kind of task you're is one which can be easily parallelized, whether or not the program you're using uses multiple cores efficiently, whether the task is memory intensive, IO intensive, or both, and on and on and on.

Working on a huge image in Photoshop CS 5? The more cores you have, the faster it will be.
Playing a game which can only use two cores? Then the 6 core 3.33 with Turbo Boost is your best bet.
Doing video editing, which uses all the cores and memory and storage you can throw at it? Maxed out 12 core is the way to go.

I think there are two ways to answer this. If cost is no object, then get the fastest 12 core machine you can, stuffed full of RAM, because as more and more applications become multicore aware, you will have the cores to make them happy.

If cost is an object, which it probably is, then look at what you intend to do and get the most bang for the buck for your intended purpose. If you're not going to run programs which will use all those cores, then don't waste the money.

[P]

Turbo boost is basically irrelevant here. Turbo boost means increasing the clockspeed one or more "bins" (one bin is 133MHz) when certain cores are inactive. The 8-core has a Turbo boost set up of 1/1/1/2, the 6-core of 1/1/1/1/2/2 and the 12-core of 2/2/2/2/3/3 - too small to really change the order between the chips. Say that you run 6 threads with perfect cooling: the 6-core can boost 1 bin, the 8-core can boost 1 bin and the 12-core can boost 2 bins. In all, the 12-core gains 1 bin, but it was 3 bins behind the 6-core to begin with, so it's still slower. Say it's 4 threads instead - the 12-core can now boost 3 bins and the 6-core only 1, but the 12-bin is still 1 bin behind.

The fastest chip, if you run 6 threads or less, is the 6-core. The 8-core is slower, but has a higher system memory bandwidth and a higher memory ceiling. It's your call which is the most important.

[Eden Aurora]

so the 6 core does have turbo boost?
from the description online, it looked like only the 8 &12 had it.

[P]

The 6-core has turbo as well. In fact, every Mac Apple makes right now except the Core i3 iMac has turbo boost. Even mobile 45nm Core 2 CPUs have turbo, except they call it "Enhanced Dynamic Acceleration Technology".

[Westfoto]

I'm with Don

What are you going to use it for? Then get the machine for the job. I think we all lust after the fastest computer like some lust after a sports car. But what good is a sports car if you are in car pool line picking up kids at school. Again get the machine for the job.

[Veltliner]

Doesn't a dual 8-core have a higher bandwidth in regards to RAM than a 6-core?

I'd also take a look at the lower RAM ceiling of the 6-core (I heard it's as low as the 4-core: 16 Gb).

How about investing in an SSD drive as a start-up disk? This should speed up things considerably.

[Don Pickett]

Just taking a quick look at store.apple.com, it looks as if the single quad- and six-core machines are limited to an official 16 GB of RAM, while the dual four- and six-core machines can take 32 GB. Looks like the limit is the number of RAM slots on the motherboard and not anything else.

I think another thing which needs to be taken into consideration is the actual utility of extra cores. At the moment there is precious little software which will use six cores well, never mind eight or twelve, and most of those have been mentioned: Photoshop, video and audio editing, serious programming, etc. For every day use, I don't know if any of us would notice the difference between a four-core machine and a 12-core machine. I don't even know if I'd see the difference between a four-core machine and my five-year old, dual processor G5.

Is there anyone out there who really understands the advantages of massively multiple cores in everyday use?

[Westfoto]

Don

There is a big difference between today's Mac Pro and a five year old G5, very big dig difference.

[Don Pickett]

Originally Posted by Westfoto 

Don

There is a big difference between today's Mac Pro and a five year old G5, very big dig difference.

I know there is. My point was: if you want to take money into account--as all of us do--then at what point do you get into overkill. Fr'instance, will you see a real performance difference, in your every day work, between a single six-core machine and a dual six-core machine?

[mduell]

Originally Posted by Don Pickett 

Doing video editing, which uses all the cores and memory and storage you can throw at it? Maxed out 12 core is the way to go.

Memory capacity and storage are useless for video encoding. Typically HD encoding only needs maybe 750MB. I guess you could use 3GB doing 4k encodes.

Cores help, especially if you can do more than one encode at a time. The higher clocked 6-core may finish the encode first since current encoders don't scale that well over 6 threads, but with the 12 core you can do two at a time for better throughput.

[Eden Aurora]

On a daily basis, i use mostly use the iLife programs, web and word processing. Occasional photoshop. And i'm really not even in the market for a new machine...but was just more curious than anything else.

So, if I had a 6 and 12 core machine in front of me right now and i use iPhoto...which would work faster. that's the question.

[P]

Originally Posted by Eden Aurora 

So, if I had a 6 and 12 core machine in front of me right now and i use iPhoto...which would work faster. that's the question.

In theory the 6-core (from clockspeed), unless you for some reason need ginormous amounts of RAM. In practice it's too close to call.