On the other hand (see above VirtualRain post), it is possible to create a pretty nice workstation, as I recently did by upgrading my older 2008 Mac Pro to a new 2012 Mac Pro. Many of the internal upgrades simply transferred from the old 2008 without problems.
I was lucky to get in on the 1 day
33% off sale by Best Buy and Amazon for a 2012 12-core 2.4GHz Mac Pro. I pulled and sold the CPUs for $800 and replaced them with a pair of 3.33GHz Xeons. I also pulled and sold the RAM and installed 48GB of new RAM. I also sold the video card and replaced it with a GTX 680.
Everything else came out of my old 2008 system. I have a 1TB SSD RAID-0 SATA-III on a Sonnet Pro PCIe card for my photo library. I boot OS X from a 512GB SSD (840 Pro on MP tray) joined into a "DIY Fusion" drive with a 4TB hard disk partitioned with half managed by Fusion, and half with static media files. I have another SSD in the optical bay booting Windows 8 for some programs I need and for games. I have the Caldigit eSATA / USB-3 PCIe card which seems to be working for me. I have a pair of hard disk drives in RAID-0 for fast local TimeMachine backup, and also do TimeMachine backups to a Synology NAS in the basement.
I could put the boot SSD on a Apricorn Velocity Solo x2 card for more speed (according to benchmarks), but I have tried it and it seems just as fast on the backplane and leaves me with an open PCIe slot. It also boots a bit faster as it takes awhile for the system to recognize "external drives" such as on the PCIe bus.
The nature and file size of my photo library is noticeably faster on the SATA-III RAID-0 SSD card (see benchmark). The RAID-0 SSD on the Sonnet card is also bootable, but I don't really
notice any speed advantage with OS X apps over the single SSD in a Fusion array (or separately, I have tried them all
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).
I am happy with the new system and glad I was able to obtain it.
-howard