My Desktop DAW PC Specifications (June 2013 Edition)

UPDATE (2013.12.28): I just made a new post about my current DAW PC setup. Some things have changed since I wrote the following article.
UPDATE (2015.08.16): And I eventually built a brand new DAW PC.

It's been over a year since my original post about my DAW setup, and a number of things have changed since then, so here's the current situation:

I'm still using the same home-built PC from early 2010, with some minor changes. It's held up surprisingly well. I routinely produce projects that have 30-50 tracks of mixed VSTi and audio, and dozens of processing plugins with smooth, consistent operation. I've only ever had to freeze VSTi tracks to audio once- in a project where every instrument part was either an instance of Native Instruments Massive or Reaktor. The only thing a new PC would get me is the ability to run more VSTi instances simultaneously, but as long as I'm able to freeze tracks as needed, that's a low priority.

PC Hardware

• Processor: Intel Core i7-950 @3.06 GHz (Bloomfield family, 4 cores, 8 threads). I'm using the factory heat sink.
• Motherboard: Gigabyte GA-EX58-UD5. Plenty of room and plenty of slots. Also has Texas Instruments FireWire, which is considered to be the best chipset for digital audio. Socket 1366 supports Intel Gulftown and Bloomfield processors.
• Case: Antec P183. Quiet and sturdy with isolated areas for power supply and hard drives, to reduce noise. I'm using the fans that came with the case.
• Hard drives: I replaced all three of my original 500GB drives with 7200RPM 2TB drives by Seagate and Western Digital. I got these all out of necessity, and in emergencies due to space requirements. The next time I build a PC I will use only WD Caviar Black drives (still the standard for fast and quiet) but the ones I'm currently using are fine for now.
• Power Supply: Corsair HX650. Relatively quiet, with all the power this computer will ever need. Wonderful modular cabling; you only use exactly the number of wires you need.
• RAM: Two Kingston DDR3 1333 sticks @ 6 GB each, for 12 GB total.
• Wireless: Linksys WMP600N Wireless-N PCI Adapter with Dual-Band. Reliable connection, with good range. I do not have any of the audio problems some people report with their WiFi adapters.
• Optical: Plextor PX-B320SA Blu-ray Disc Combo. BD reader, and super multi writer.
• Video:  Currently using an ATI Radeon HD 5700 graphics card to power two monitors. The drivers for the NVIDIA card I had before were conflicting with the drivers for my PCIe audio interface on both Windows 7 and Windows 8. This card is actually a downgrade in terms of graphics power, but it uses less electricity and is quieter than the NVIDIA card, and I hardly ever play games these days.

Audio and MIDI Hardware

• MIDI Controller: I sold my AKAI keyboard controller for a much simpler Roland A-49 keyboard controller. I thought the AKAI was a fine device, but it was enormous due to all of its pads and faders and other controls which I simply never used. I traded the AKAI's enormous feature set for the Roland's light, slim design to reclaim some serious desk space.
• Audio Interface: The, MOTU 24 I/O PCIe Core System , which includes MOTU PCIe-424 interface with the 24I/O expander. The PCIe-424 is a low-latency interface card that can have up to four expanders connected, presenting them all to your DAW as a single mega interface. The 24I/O doesn't have any preamps or effects (or even a headphone jack!) like my old interface- it is simply 24 balanced analog ins and 24 outs. Most of my hardware synths are connected directly to the 24I/O but I had to connect some of them to a patch bay, and I route them to the interface as needed.
• DAW Controller: Steinberg CMC-AI controller . This small little controller has what Steinberg calls an "AI knob" which can serve as a jog wheel or as a universal controller for just about any knob or fader in a Steinberg product or a currently-focused VST plugin. The bad news is that it is Steinberg-specific, and can't be programmed to work in other DAWs.
• DAW Controller: KORG nanoKontrol2 . I got this because I wanted a physical device with transport controls for Ableton Live. It has built-in templates to integrate with all major DAW packages, and also includes buttons for setting and navigating markers/locators in audio projects, plus 8 rows of channel strips which map to tracks inside your DAW. A really handy little controller, at an unbeatable price.

Software

• Operating System: Windows 7 Professional 64-bit, with Service Pack 1. The 64-bit version of Windows 7 delivers the best balance between power and performance, and gives you access to as much RAM as you're able to cram into  your computer. Most DAWs have 64-bit versions these days, and an increasing number of plugins come in 64-bit formats as well, offering more memory flexibility and occasionally faster performance. I've only recently made an across-the-board move to 64-bit applications and plugins, although this means I've had to turn my back on a number of plugins that still don't have 64-bit support. (I'm not interested in bridging solutions at this time.)
• DAW: Steinberg Cubase 7 . I've been a cubase user since the very first release on Mac in 1994, although the Cubase of today is wildly different from the MIDI-only Cubase of the early 90s. After some tweaking I seem to have 64-bit Cubase 7 running pretty stably. Version 6.5 seemed a little bit more reliable, but I'm doing okay for now.
• DAW: Ableton Live 9 Suite . With version 9, Ableton Live added some really interesting new features and significantly improved a number of their built-in effects. I've completed several productions in Live 9 and have found it to be a really enjoyable environment. Both Live 8 and 9 offer 64-bit versions now, too! I just really wish Live had VST 3 support; a number of plugin developers only offer 64-bit plugins in VST 3 format, so Live's VST compatibility isn't the greatest.
• VST Instruments: Far, far too many to mention. I can strongly recommend the Native Instruments Komplete packages (especially Komplete 9 Ultimate ). They really cover all the basics for software synthesis, and include a growing number of solid effects, too.