There were some interesting comments on slashdot regarding a DIY build:
noise levels, all over finish, blue screening due to drivers, hardware incompatibilities, support and maintenance etc
And I would have to agree. If you're a hobbyist then by all means go DIY and fiddle to your hearts content.
If you're a business user with deadlines to meet, get the mac
Blue screen due to drivers...LOL! That's a Windows thing. Does not happen to PC's running OS X. The blue screen equivelant in OS X is a Kernel Panic. The screen you're on freezes and a load of text rolls down with a message to restart your computer. Not a blue screen, unless you happened to have a full screen of a blue background.:wtf:
KP's only happen due to a poor choice in hardware, or conflicting drivers and not merely because you are using 'PC' parts. (all PC's , Macs included, have PC parts). But once you know which configuration to build, KP's are a thing of the past. In fact, most popular configurations have become hassle free due to Apple including support for a larger variety of chipsets in their newer iterations of OS X.
The noise level of any PC is determined by what you use to cool your hardware. Most PC's nowadays are so silent, you would not even know it was on if not for the lights. You obviously only have experience with the cheap n nasty PC's which have noisy fans. With decent silent fans, you would have to be OCD and put your head against the case to hear the PC.
In Tiger, it was an absolute nightmare to get a desktop on OS X up and running close to perfect. Since Snow Leopard though, it became easier. From Mountain Lion to Mavericks, everything can run 100% perfectly without much to configure. In fact, only sound drivers need modding. The rest, if you by wisely, 'just works'. (the old Apple catch-phrase is so corny!)
The only reason not to use a self-built Mac-Pro for business use would be the legality involved. As for support, anyone who can build a Mac Pro from scratch is in a position to provide hardware support. If anything dies, you can pick up off the shelf replacement items from most PC suppliers -
same day repair! If it were not for the legal aspect, the ability to repair a OS X desktop within a few hours as opposed to how long an Apple repair centre would take, would make even more sense for business use than an imported Apple Mac, where spares are not always in stock at repair centres. Especially if you do not have a repair centre close to you or in the town / city where you live. The cost... well erm! Sooooo much more cost efficient. Just compare the price of a standard PC motherboard replacement to that of a Mac. On a Mac, you have to pay for a new 'logic' board as well as processor, seeing as they are integrated. Only reason they are integrated... Apple does not want you to upgrade.
Warranty... most PC components have a 3 year warranty. On a Mac... 1 year. On a repaired mac... 6 months. Unless you pay them some more for an extended warranty. Pay pay pay!
The deal-breaker... self-built Mac-pro's have much better upgrade options, expandability and can run with far superior components at a much lower cost. Apple does NOT use the most high-end components on the market. They take the best deals they can from a number of suppliers based on cost and delivery, not quality. Just go to any mac tear-down article.Gizmodo has one. You would be amazed at what they throw inside of a Mac these days. i-Macs have standard laptop components and Mac Pro's have standard PC components. Only the board configuration changes so that connections and plugs are located to best suit their exterior design (the case). Chipsets are all standard 'PC' chipsets like Intel, Realtek, Atheros, Broadcom, NEC etc. This is why hackintoshing is posiible in the first place.
If hackintoshing was completely legal, you would have access to better OS support as well. There are things I have learnt from the hackintosh community that would stun the most experienced Mac support technician.eg. Hackintoshers were the first to have USB 3.0 support on their systems at a time when Apple were trying to convince their following that USB is on the way out and had no intention of providing drivers. A brilliant coder from insanelymac modified a third party exclusive driver to work on any mac / hack. A year later, Apple implemented USB3 in their next line of Macs and used part of the universal USB 3.0 code in their own drivers. It is absolutely shocking to see how little Mac owners actually know about their OS, not to mention Apple OS support... I have fixed things on my genuine Mac-Pro that would leave Mac OS support staff speechless. They are not the wisest at the best of times. They learn text-book style and cannot think out of the box. (or may not be allowed to).