I am not sure if this has been posted or not but you CAN undervolt the A7N8X-E DLX with the nVidia System Utility (NVSU).
A few notices...
I am not certain if this will work with the non-E A7N8X DLX as the nVidia System Utility does not fully support this mobo.
This procedure only works with the nVidia System Utility and NOT the nTune software.
There are a few catches... they will be mentioned later on.
There is always a risk involved so no guarantee this is going to work...
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The procedure is as follows:
1) Download the latest NVSU (should be v1.08.5). Execute the .exe program - the installation files will be extracted to your temp folder BUT DO NOT install it yet.
2) Pop in your Asus A7N8X-E DLX CD, and in the directory <cd drive >\Software\NVSU, locate two files:
- OEMLogo.bmp - This is Asus's custom logo for the NVSU program. Feel free to edit it to your heart's content.
- nvsuoem.ini - this configuration file allows the NVSU to recognize your mobo as the A7N8X-E DLX and unlocks some of the settings. The most important setting that is unlocked is the VCore adjustment.
3) Copy nvsuoem.ini and OEMLogo.bmp to the temp. directory that contains the installation files of the NVSU. Click OK when it promps you to overwrite the existing files.
4) Install the program and volia... you can now undervolt your A7N8X-E DLX! (See interface below)
Currently I am running a Barton 2500+ (non-mobile version) .
My config is as follows:
Barton 2500+ on ALX-800 w/Low Speed Sunon Maglev
Asus A7N8X-E DLX Rev 1.01
1 x 256 MB DDR PC2700 Micron
MSI FX5200 T-128 (passive cooling)
LG 52x CD and LG 52x32x52x CD-RW
1 x 800JB (whiner edition)
1 x SP1614N (JVC motor but still very quiet)
Enermax EG365P-VE 350W dual fan
"Ferric Sigma" 18' ATX - 2 x Sunon Maglev as intake, 2 x Arctic Fan Pro 2L (on Low settings) as exhaust => All connected to Zalman 6 channel fan controller
Now here are the catches (any values displayed are based on my Barton 2500+, different values may be displayed with different CPUs):
1) Even though the VCore values go as low as 1.425V, I wasn't able to apply any settings below 1.500V (you get an error that says this setting isn't stable or something like that).
2) I think the software program makes a call to the configuration file and attempts to make the adjustment to the BIOs. Since no A7N8X-E DLX BIOs (be it from Asus or Modded) supports a VCore Value lower than 1.650V, you *MIGHT [edited] get a CMO error when you restart your computer (BIOs will be resetted to its default value). Hence, make sure you reset the VCore back to the CPU's default value before shutting down or restarting your computer. I had no problem bring my computer from a standby mode with VCore = 1.5V though. This leads to the third point.
3) You have to re-apply the settings everytime you restart your computer. It's too bad that the NVSU doesn't have a feature similar to the AutoFSB on the 8rdavcore (
http://www.hasw.net/8rdavcore/). You might wanna make a batch file that starts and apply the desired settings upon startup/shutdown. Don't look to me yet... I have crappy programming skills

...
By dropping the VCore from 1.65V to 1.5V, I was able to shave about 3 to 4 C off my idle and load temp. I'll update this post after more testings.