Inside, Apple took advantage of the cavernous chassis to keep riffing on the “you want it, we got it” theme. The system has four full-length PCI Express slots, one of which is double wide to accommodate large graphics cards without wasting a usable slot. One of the primary criticisms I expressed related to Power Mac G5 was the poor design of the card cage, specifically, that the tiny, non-standard screws holding the cards in place stripped too easily—an unrecoverable condition, I learned—and were too weak to hold cards with heavy cables that would be frequently plugged and unplugged. Now Apple holds Mac Pro’s cards in place with a single metal panel secured by two thumbscrews. Little things mean a lot to people like me who demand unbreakable hardware.
Mac Pro adds room for a second parallel ATA optical drive, including a second garage door that opens and closes when discs are inserted and removed. Mac Pro uses full-sized, tray loading drives, so you can add your own as long as you can pop the drive’s face plates off. Of course, you can also snap the tray when you don't know it's out (the tray is black and easy to overlook), a fact that makes slot-loading drives look rather smart. On the other, other hand, slot-loading drives can only accept 5.25-inch discs.
Will you be having the 250 gigabytes, or the three terabyte special?
Hearing the cry of workstation users that they never have enough storage, Apple made room for four Serial ATA drives inside Mac Pro’s chassis. That’s not unheard of; a full-sized tower Opteron workstation in my shop has five drive bays. But Apple put six bays in a mid-tower box by lining up a row of four easily removable, zero cabling drive trays just above the expansion card area. The trays are precisely the size of 3.5-inch hard drives and—get this—Apple does not require that you purchase Apple-branded drives. All Mac Pros come with four trays, and you can fill the empty ones with off-the-shelf SATA drives at will. SATA drive densities are rising at a dizzying pace, and with the present ceiling at 750 GB, you can stuff a Mac Pro with a remarkable 3 terabytes of storage. You know you’re a true workstation user if you greet that figure with, “is that all?” Yes, you’ll have to make do with 3 TB for now. (at this writing, Apple maximum drive size is 500 GB)
Mac Pro uses 667 MHz fully-buffered DIMM (FBDIMM) memory, as is standard with Woodcrest systems. Using a very fast serial bus, FBDIMM has a lot of potential, but its advantages over more widely-used DDR2 are sometimes exaggerated. However, FBDIMM serves Woodcrest's shared-bus design well, because there wasn't much more parallel bandwidth Intel could pull out of its design. As is generally true, FBDIMM trades performance for heat and power draw, but in a two-socket design like Mac Pro the difference is insubstantial.