Two of the several computers I own is the original PowerMac G5 1.8GHz, as well as an AMD 64 3200 home built PC. Both these machines uses two 7200 rpm SATA IDE hard disk drives. I am busy doing an FTP from the Windows machine connected to the G5, retrieving a 22GiB file.
Both CPU's are running at approximately 80%, and the network utilization is a constant 18MBps. The interesting thing is that after 3 minutes of copying the PC started making 1 second interval beeps on the internal speaker. This is the thermal warning function built in to the Gigabyte motherboard when the temperature exceeds 70C. The statement I want to make is that the G5's fans are all idling slowly, the system is completely cool and way within spec. I cannot really see any thermal difference to the normal state. Luke warm air is being expelled from the rear fans. However, the AMD is overheating. The hard disk drives are so hot you can boil eggs on them.
The reason? The G5 was designed with thermal considerations in mind from the very beginning. The PC however, received no such attention. You may argue that the G5 costs 5 times as much, but then again PC manufacturers had more than 20 years to get the thermal design of a simple mini tower correct. How difficult can it be to design a case that has good thermal properties? The basic principle is simple - you need to suck in fresh, cool air, let it pass over all hot components internally, and gently blow out the hot air on the other side of the case. This is exactly the same principle used in cooling towers of power plants.
It will cost about R100 more to build a standard PC case that is thermally well designed. Is that too much to ask? I know you can buy a Dell and away goes the problem, but how many people uses Dell's for their desktops?
I will never buy a component PC again. Next time will be either another Mac, or a Dell.
[Update] 1 minute after I wrote this article - the AMD has just died. One long continuous beep and then the system shut down. A quick look in the BIOS confirmed my postulations - the CPU is at 96C.