Another thing to think about for OS X use when comparing a PM G4 to PM G5s:
All graphics cards that shipped with the G5 supported core image, even down to the FX5200 that shipped in the earliest, low end G5s.
By contrast, in the MDD era the standard shipping card was the Radeon 9000, which does NOT have CI support. Even the high end BTO card for much of the MDD era-the GEForce 4Ti 4600(a personal favorite of mine) doesn't have CI support. The Radeon 9700 was a BTO card on some MDDs(I think only FW800 models) and does support CI, but the factory version is quite uncommon. The retail Radeon 9600 PC&Mac also supports CI.
To my knowledge, these two are the only plug and play CI cards for a PM G4.
There are other options, but nearly all involve taping pins(and possibly other modifications) and often flashing PC versions of cards.
The G4(Quicksilver) I'm typing this from has a Radeon 9600XT out of a G5. I had to tape pins on it to get it to work, and also had to modify it somewhat to get it to supply power to my ADC display.
One of my Dual 1ghz MDDs has an ATI FireGL X3, which required flashing(it's recognized as a Radeon X800 after flashing-one of the best AGP Mac graphics cards), and also taping pins to work in a G4. This is a fantastic card, but again is not plug and play. It performs even better in a G5 since the G5 gives it a full 8x AGP bus.
I have one other Quicksilver using a PC&Mac 9600 Pro, although this card can be touchy to get working in a Quicksilver or Digital Audio(and won't work in anything earlier). I actually couldn't get it working reliably in a couple of other Quicksilvers. I have two of these cards, and may try the other in my upgraded Digital Audio.
My B&W G3 with a G4 upgrade has a flashed PCI FX5200(with 256MB of VRAM), although the PCI bus is a bottleneck to the performance of this card.
There are a couple of other options. I think Erik has a 9800 in his Quicksilver. If I can ever get around to it, I'm going to flash an NVidia 6200 for one of my Cubes.
In any case, with all that rambling the point is that Leopard runs a LOT better with a card that supports CI. It even helps-although to a less extent-in Tiger. The reason is that the computer can offload a lot of the GUI elements to the GPU and free up the CPU to do actual computational stuff.
One last thing-I have two scanners connected to my most-used Quicksilver. One is an old SCSI slide scanner, and the other a USB flatbed than can scan transparencies(negatives or slides). I use 3rd party software called Vuescan that allows me to do things like multi-pass scanning and also has built in color correction filters(for old slides and negatives) that are better than anything I could do manually. When I'm using the flatbed, it makes a minimum of two passes-one to scan the image, and the other an infrared scan that sees dust and scratches. The software then subtracts the IR "background" from the image. When I'm dealing with a thin negative or a dark slide, I will often do at least three scanning passes(in the visible range) to increase the signal/noise ratio and sometimes even 10 passes. Vuescan then has to combine all of these individual scans into one image. Vuescan is a good program and fully utilizes all processors present.
I can speak from experience when I say that it takes Vuescan about 1/3 the time to process a 3-pass scan+IR(four passes total) on my single 1.8 G5 as compared to the dual 1ghz Quicksilver.
The only reason is that I keep using the G4 is because
1. SCSI on a G5 requires an expensive card. The Quicksilver I use has an original BTO SCSI card, but if not pretty much any $10 SCSI card from Ebay will work(at least under Tiger).
2. I've done so much of this type of work on the G4 that it's convenient to keep it all in one place. I've actually changed the G4 twice along the way, but in every case just transplanted the hard drives and kept going on my way.
3. My set-up with the G4 is much more conducive to scanning film(which is NOT just as simple as dropping the film in the scanner). I have a light table, loupe, and compressed air handy-all things I wouldn't have with the G5.
That's just another anecdotal experience, but bear in mind that it's with a faster G4 than a dual 867 MDD and with the same speed FSB. I think the only advantage the MDD would offer is an extra 512mb of RAM, and possibly the ATA/100 bus(although I don't think any IDE HDDs could saturate an ATA/66 bus-some late ones came very close).
Compare that with a G5, which has a much faster FSB(again, half the clock speed), a LOT more ram(2x for the lowest end G5 vs. an MDD or Sawtooth, 4x or even 8x in some G5 models), faster RAM(PC-3200 for most and PC2-4200 in the last generation, compared to PC-2100 in an 867mhz or single 1ghz MDD or PC-2700 in higher spec MDDs), and a SATA bus that's not only faster but can also use modern, fast drives.
(I did never own G5s for a long time, but two G4s). I was just wondering. Handbrake does good usage of multiple cores, it could be a good test to compare the MDD with the low end G5. you can find a short testfile in the DIY benchmark thread here in the forum. But if you say for the stuff that you do, it works, than it is ok.
