I have two computers at the moment, a dual-core Athlon X2, which I will refer to as the "X2" from here on, and the dual-core PowerMac G5, which I will refer to as the "G5" from here on. The specifications of the two machines are as follows:
X2: Processor: AMD Athlon X2 4400+ @ 2.2 GHz Motherboard: DFI LanParty nForce4 Cache Memory: 1MB of full-speed on-die L2 per core System Memory: 2GB of CAS2 DDR-400 SDRAM Graphics Card: Gigabyte GeForce 6600GT 128MB Hard Drive: Seagate 7200.8 250GB SATA Optical Drive: MSI SATA CD-RW Power Supply: Seasonic S12 380W Case: Antec P180 Operating System: Ubuntu AMD64 5.10 G5: Processor: IBM PowerPC 970MP @ 2.3 GHz Motherboard: Apple Proprietary Cache Memory: 1MB of full-speed on-die L2 per core System Memory: 2.5GB of CAS4 DDR2-533 SDRAM Graphics Card: Apple GeForce 6600 256MB Hard Drive: Western Digital WD2500JS 250GB SATA Optical Drive: Pioneer DVD+RW Power Supply: Apple 600W Case: Apple PowerMac G5 Case Operating System: Mac OS X 10.4.3 Shared: Monitor: Dell 2405FPW LCD @ 1920x1200 Keyboard: Cherry Cymotion Xpress Mouse: Microsoft Intellimouse
In short, the two machines are very comparable in specifications. with the main differences being that the G5 has a DVD burner, while the X2 has the much faster "GT" version of the GeForce 6600 graphics card. It would seem that the G5 also has a much beefier power supply, but in reality, power supply ratings are about as reliable an indicator of performance as megahertz ratings, so no comparison can be made between the two without further testing.
From the outside, the PowerMac G5 is a beautiful machine. It is entirely aluminum, brushed to a gorgeous silver-white color. The perforated front contrasts nicely with the solid sides, and the white pulsing power light is a sophisticated accent. The machine is as solid, and heavy, as a rock. The side panels and handles are made of what appear to be 1/8" aluminum plate. Anybody who knows aluminum knows that 1/8" plate is serious stuff. It can easily support the weight of a man, and getting it to curve in the way the G5's handles are curved requires a two-ton press. All in all, the G5 looks more like an expensive piece of audio equipment than a computer.
Unfortunately, the G5 doesn't just like to be seen, but heard as well. The G5 is very loud compared to the X2. I somewhat expected the G5 to be louder, since I have optimized the X2 very intensively for silence, but it was louder than I expected. From an acoustic point of view, the G5's noise issue are the result of a few critical failures in case design. The primary problem is the cooling system. It is very elaborate, with nine fans, a huge dense heatsink, and numerous air guides. It is entirely too much for a processor that supposedly has a thermal design power of 100W, and its overkill factor makes for a lot of unwanted noise. In comparison, the X2's cooling system is built using a few simple principles of silent computer design. First, there are only three fans, and they are large, slow ones that move a lot of air at low speed. Noise is a 6th order function of air velocity, so making a fan twice as big but half as fast can result in a huge decrease in noise. Second, the X2 uses a large, but free-flowing heatsink. Turbulent airflow through a heatsink creates a lot of noise, and a constricted heatsink like the G5's is noisier than a freer-flowing one like the X2's.
A secondary problem is the case. The G5's fancy aluminum case is an acoustic disaster. Plate aluminum is a very rigid, and thus very "loud" material. To compound the problem, there are few noise treatments on the inside of the case. Parts are mounted to the aluminum frame without isolation devices, ensuring that every slight vibration will be magnified into an audible annoyance. With nine fans and a noisy hard drive, there is plenty of vibration for the aluminum case to amplify. The X2's P180 case, in comparison, is designed for silence. It uses a composite construction of plastic sheets sandwiched between aluminum ones. These panels dampen interior case noises instead of amplifying them. Inside the case, everything that can vibrate is mounted using soft silicone pads or grommets. These ensure that vibrating components are isolated from rigid structures, suppressing vibration noises.
A tertiary problem is the hard drive. It is a cheap Western Digital unit that is extremely loud. It can be heard while merely spinning, and when seeking it is distractingly audible. In comparison, the Seagate in the X2 is silent while spinning, and its seeks can barely be heard without listening carefully. In all, the G5 is barely tolerable from a noise perspective. Many people would find it adequate, even quiet, but gamers with 100 CFM Tornado fans don't count, and I point to the popularity of silent computing websites as evidence of the fact that more and more computer users are becoming noise-conscious. One doesn't even have to build their own computer to find a quieter machine than the G5. There are three Dell Dimension Pentium 4 machines in our apartment, and every single one is quieter by a large margin than the PowerMac.
Moving on to the inside of the machine, I would like to point out a few things about parts quality. There is an idea floating around that Apple somehow uses particularly high quality components. I find that idea to be a inaccurate. It is true that Apple uses a very high quality case, heatsink, and motherboard PCB, but that is about it. The hard drive in my PowerMac is, as I mentioned, a cheap Western Digital unit. If you type "250GB SATA" into Froogle, it is the unit that comes up at the very bottom of the price list. The fans are run-of-the-mill Delta pieces with audible bearing noise. The RAM is mix of generic and Crucial. I'll leave it to the reader to guess which brand came with the machine, and which brand I added. The keyboard is light, mushy, and its keys do not spring back with conviction. The mouse is lightweight and has a very flimsy-feeling scroll nub. The X2's components are superior in almost every regard, save perhaps for the motherboard and heatsink. The case is superior in the areas that matter, notably expandability and noise. It uses name-brand low-latency memory, a quiet Seagate hard drive, and a very efficient and quiet power supply from a company well-known, to silent computing folks, for the quality of their products. It uses fans that are $10 apiece, but worth every penny for their high-quality, silent bearings. It uses a keyboard heavy enough to wield in self-defense, with real German-engineered key switches that spring back as soon as pressure is released. It is, in short, a very high quality unit.
I have no problem with paying a premium for a premium product. I love my iPod, and think they are worth every penny, because their hardware really is superior to what is available in competing players. However, I cannot say the same for the PowerMac. Aside from the aforementioned case and cooling system, there is nothing in there that you wouldn't find in a Dell.