I have the P5Q3 motherboard Deluxe with WiFi-N which is the same as the P5Q Deluxe but mine runs on only DDR3 ram, the difference I have noticed between a non-phase to the 16 phase is a lot less power when the system is in idle. I am one of those people who always forgets to set to hibernate. I have noticed when all the features active when I am way that my system idle goes down 80% lower than it was previously. To me it is more of a concern about they are trying to make "More Green Solutions". The higher the phase number the lower the system will use wattage for that resource, but also about these board when they are in use they will not suffer at load. I am not really answering your question, but more or less answering from my experiences with it. If you're the kind of person is in and out away from the computer, who who doesn't use the computer all the time but leave it running you'll certainly benefit with a higher power phase number, but also if you aren't using your computer with high load alot you'll see energy savings on your electricity board.
Now I am going to compare the 2 boards you indicated to evaluate and give you a detailed response of these 2 boards from Asus' specifications and features and compare contrast the two.
The ASUS P5Q3-E
* Intel LGA775 Platform
* Intel® P45 chipset
* ASUS 8-phase Power Design
With power efficiency so important to operating temperatures, ASUS 8-phase VRM design leads the industry with its 96% power efficiency. High quality power components such as low RDS (on) MOSFETs for minimum switching loss & lower temperatures, Ferrite core chokes with lower hysteresis loss, and high quality Japanese-made conductive polymer capacitors all add up to ensure longer component life and lower power loss - creating more energy efficiency.
* Dual-channel DDR2 1200/1066/800/667 MHz
* 100% Japan-made high-quality Conductive Polymer Capacitors
* ASUS EPU-6 Engine
* ASUS Express Gate
* ASUS Drive Xpert
The ASUS P5Q-Deluxe (DDR2)
* ASUS True 16-phase Power Design
*ASUS True 16-Phase Power Design
Unprecedented Innovation with the best quality component for best performance
The breakthrough technology of 16-phase VRM design is bringing to the ASUS
motherboards. 16-phase power design can reach the power efficiency up to 96%+, and
dispel heat generated by VRM module effectively, and lower more temperature compared to
other VRM solution. With the high quality power components such as low RDS (on)
MOSFETs, Ferrite core chokes with lower hysteresis loss and 100% Japan-made high
quality conductive polymer capacitors, ASUS 16-phase VRM design also ensure longer
component life, minimum power loss, and help to reach the superior overclocking score ever
* ASUS EPU-6 Engine
* ASUS Express Gate SSD
* ASUS Drive Xpert
* 100% Japan-made Solid Capacitor(5000 hrs VRM)
* AI Nap
Minimize noise and power consumption when temporarily away!
With AI Nap, users can instantly snooze your PC without terminating the tasks. System will continue operating at minimum power and noise when user is temporarily away. It keeps downloading files or running applications in quietest state while you´re sleeping. Simply click keyboard or mouse, you can swiftly wake up the system in few seconds.
(this is the feature I was talking about, but it works a lot better than windows Hibernation, and actually has never crashed for me).
* DieHard BIOS
BIOS Never Die
The ASUS Diehard BIOS consists of two BIOS chips, a main BIOS and a backup BIOS. The ASUS Diehard BIOS can restore corrupted main BIOS data from the backup BIOS automatically. The technology saves users the hassle of recovering the BIOS file or buying a replacement BIOS chip.
* PCIe 2.0
This is just a start but here is a link between the 2 different motherboards
Personally from viewing these 2 boards there are a lot of similar features, but by far the Deluxe board comes with many notable features which makes the board a bargain for even $40 more. The idea of the phases is to save money. How much between the 2 boards you'll save, not too sure, but why not be "A Power Saving Hero".
You I might have missed other things, but these boards have both very simuliar features. Anyone else here wanna stab on finding other difference with these boards?
Interesting. But the P5Q-E is not "non-phase", it's 8-phase, just not 16. So it should still idle at lower power overall, maybe not as much as the 16, and yes, I do leave my computer on all day every day and sometimes overnight, but I wonder if the extra 8-phases make a huge diff.
I can understand the diff. between the non & and the 16, that'd be much bigger than the diff. between the 8 and the 16, do you agree? Maybe I'll just get the deluxe and eliminate any doubts though, it's gonna be a board for my new comp for at least 5 years so it should increase lifetime to other components supposedly as well.....hmmmm