02-22-2008, 05:27 PM

I have a 8 core mac pro and its going pretty slowly when it comes to rendering video, the processor meters are indicating that it never goes higher the 45%.

Could anybody shed light on why this is happening? I really need more speed and less engergy conservation right now. I'm trying to get work done.

02-22-2008, 07:01 PM

How many threads does the rendering software have? If for example the software only runs in 4 threads, and you have 8 cores, and OS X is an equal opportunity scheduler, you would never see more than 50% occupancy on any one CPU. This is likely what is going on, and is the real fallacy of the "more cores = more power" approach. You can only utilize more cores if the software is written to take advantage of them all.

A less likely possibility is that your machine is maxing out in some other area and so can't utilize the full CPU availability. Perhaps it is hitting the limit of available RAM or the maximum throughput to disk. Is there a way to measure that?

My money is on thread limitations - your software is likely coded for four threads and you are just spreading them across 8 cores, resulting in a low average per core occupancy.

It is for reasons like this that I remain interested in raw GHz. At some point, you simply need more umphh per core to result in faster overall completion of the work you are doing.

02-23-2008, 01:45 AM

Hmm, interesting. I guess final cut is coded for only 4 cores then. Hopefully an update will fix that

02-23-2008, 10:15 AM

I am going to agree with Mac57 here. Either the app is only designed to run with four cores or there is a bottleneck somewhere else. Given the new layout of the Mac Pro, it's probably the software.
I was reading an article about this issue. If an app isn't designed to make use of all the cores, it will actually be slower than a dual core model. Encoding through iTunes is slightly faster on a Core2Duo than a Xeon Quad.
This is why I decided to only get the Quad 2.8GHz. Hopefully, the next version of Final Cut will make use of all the cores. Weird though that it doesn't. The original 8 core Mac Pro has been out for awhile.
hmmm.... Is there a preferences feature in FC? I know with Photoshop you can tell it to use spare HD's are scratch disk. Is there something disabling you from drawing more processing power to conserve energy?