Mac Pro - CPU and Ram Utilisation (don't appear to be fully used)

Question

Hi,
We've recently purchase and set-up a Mac Pro running OS X 10.4.8 (latest patches), FCP 5.1.2 and don't seem to be getting quite the performance we were expecting. (Caveat - I'm a IT tech not a video specialist so apologies if I get something wrong).
A few background details
Our configuration is as follows:
Mac Pro Dual Proc/Dual Core 3.0GHz intel
5GB Ram configured as:
Riser A Dimm 1 - 1GB
Riser A Dimm 2 - 1GB
Riser B Dimm 1 - 1GB
Riser B Dimm 2 - 1GB
Riser A Dimm 3 - 512MB
Riser A Dimm 4 - 512MB
(think AFAIK this should be the best config for the ram we have?)
(Slot 1 (in x16 mode)) ATI Radeon X1900 512MB graphics
500GB Internal SATA HD
(Slot 3(in x4mode)) FC 2 GB/s Apple card to XRAID (7x500GB RAID 5 with one spare)
(Slot 4(in x4 mode))Blackmagic Decklink HD Pro
Xraid seems fine performance wise - Blackmagic disk test shows 145MB/s Read about 100MB/s write.
Anyhow we have been doing some test rendering but don't seem to get the CPU utilisation above 150% (out off 400%) and also note the RAM utilisation also seems a little on the low side (not using more than 200MB 'Real memory' (as noted in Activity monitor) and any more than 1.2GB 'virtual Memory' despite having lots available (nothing else running)).
The (DV PAL) file we are rendering is simple consisting of over an 1 hour of Sat TV footage (bout 15GB worth just to test) captured via DV to which we applied some plugin effects (Chroma key, Light Ray and Scrub) once again just to test perfomance.
Have checked all the settings I can think of -i.e. system settings > Memory and Cache is set to Application = 100% (2560MB) and Still Cache = 20% (482MB). Scratch is Xraid etc. but can't seem to find anything obvious that could bee affecting this. (Also as an aside does anyone know if FCP limited to 50% of total sys memory as it appears to be (looking at the app = 100% = 2580MB) as it seems we could utilise more (in generall)).
Is this situation be normal? - bit hard to benchmark as our other machines are still 10.3.9 / G5 based with FCP 4.x. The Video tech seems to think its not as big a difference from his Dual 2.0Ghz G5 2GB Ram (3 years old) as he thought it would be (apologies for his vagueness)
Anything I can look to change/improve - I am concerned mainly about the lack of utilisation? Everything is freshly built straight after delivery
thanks - Pete
Mac Pro DP 3.0Ghz     Mac OS X (10.4.8)

Answer 1

It probably is mostly a 32-bit versus 64-bit thing in that the big boys like Final Cut Pro, Photoshop, After Effects, etc. won't "see" more than just under 4 gigs of RAM. So they won't use memory as efficiently. A nice side effect to this is that you can multitask well with several of these apps open at once if you have a around 8 gigs of RAM.
Also DV (NTSC or PAL) isn't going to tax the system much as far as bandwidth so your maximum RAM usage probably won't be as high.
Compressor will push the CPUs harder, as will using some other codecs that are more sophisticated than DV.
Also, I'd think that the new Intels are still new enough that a lot of software might not be fully optimized yet. And in general the G5 PPC machines have a really fat memory to processor bus so that you aren't necessarily going to see a radical speed increase with these new Intel motherboards for some tasks.
If you have any CPU-based 3D apps like Cinema 4D or similar I'd try rendering tests to benchmark your CPU usage. 3D isn't as RAM intensive but it will push the four cores in my Quad G5 nicely. I'd expect the new Intel Quads to outrun my PPC Quad.