We're stepping outside of the spec sheet process to give you some more information on the PowerMac G4's design. The processor is mounted on a large daughtercard, about four times larger than the ZIF daughtercards of previous G3 PowerMacs. The heatsink is monstrous with dimensions of about 4" x 4" x 1". The machines were on all day, running intense demos with no fan blowing on them and we noticed no crashing. There is some speculation that the G4's ROM is built into the processor daughtercard, thereby making it impossible to upgrade the machine (Apple does not sell ROMs to other companies). While this is a possibility, ever since the iMacs, PowerMacs have come with ROM in RAM. Therefore we think it is a good possibility that there will be processor upgrades for G4 PowerMacs in the future. Without getting to look under the heatsink, we cannot say, and Apple wasn't giving us an answer.
Memory
64MB, 128MB or 256MB of PC100 SDRAM (3.3-volt, unbuffered, 64-bit-wide, 168-pin, running at 100 MHz)
Four DIMM slots support up to 1.5GB of PC100 SDRAM (999MB maximum per application) using the following DIMMs:
- 32MB, 64MB, or 128MB DIMMs (64-bit-wide, 64-Mbit technology)
- 128MB or 256MB DIMMs (64-bit-wide, 128-Mbit technology)
- 512MB DIMMs (64-bit-wide, 256-Mbit technology
The memory specs are actually significantly different for the low-end motherboard versus the high-end motherboard. While both machines have four DIMM slots, the high-end motherboard is capable of taking DIMMs up to 512MB and the low-end motherboard is capable of taking DIMMs only up to 256MB. For the low-end motherboard, this means you can put four 256MB DIMMs in to get 1GB of RAM. For the high-end motherboard, you would think that this means you could put four 512MB DIMMs in to get 2GB of RAM, but actually, with 512MB DIMMs, it can only take up to 1.5GB of RAM. Mind you, we use the word "only" in a very light sense.
Historically, PowerMac G3's have been very sensitive to RAM quality for larger DIMMs. The specifications and prices for 256MB and 512MB memory modules will most likely be very high. On the Apple Store web site, getting 1.5GB of RAM is an $8500 option. A mere pittance for Steve Jobs, but that's a whole lot of moolah to us.