Last night I had a near-disaster - my Benq 8700+ suddenly stopped detecting anything over DVI when attached to either one of my PCs! It worked fine on the Panasonic S97 DVD player using an HDMI->DVI adapter.
I spent 2 hours diagnosing the problem. First I reset everything in the projector to factory defaults. Didn't work. Then I tried flashing the firmware on the Benq 8700+. That didn't work either!
Good thing I wrote down my DVI input color calibration parameters!
So now I took more drastic measures - my old HTPC wasn't completely rebuilt - no hard drive in it. But it can still POST with video output. Naturally, the Benq didn't detect any video from this PC either.
At this point I guessed that the EDID information in the projector was corrupted. It took me half an hour to find the software that would allow me to boot off of a USB flash drive. I had to format it and then used the MKBT tool to write bootsectors onto the flash drive. Then I downloaded and copied the Bartman Network Boot CD files onto it, and copied the EDID Writer (ddcw.exe) software which can be obtained here:http://www.geocities.com/jgeneedid/EDID_Writer.zip
(From this page: )http://www.geocities.com/jgeneedid/#...es_and_Readers
It only works with NVIDIA cards, and allows you to retrieve and write EDIDs from and to a display.
I then used the Viewsonic EDID utility to view a backup of an EDID file I custom made for my Benq 8700, and manually entered the hex values into a text file using Windows Notepad, and copied the file onto the flash drive.
I rebooted my new HTPC with the USB flash drive (the old one cannot) in place. I then read the EDID using ddcw.exe and as I suspected the EDID on the Benq was corrupted! Instead of beginning with the usual "00 FF FF FF FF FF FF" sequence, it began with "00 FE FE FE FE FE FE", and it had a few FEs in the middle of the EDID data too. No wonder it didn't work!
I re-attached the projector into the monitor 0 port (ddcw can only write to monitor 0), and ran ddcw.exe with the "-c benq.txt" parameters to write the EDID information from the benq.txt file I made.
After the EDID was rewritten, I rebooted, and lo and behold, I got video on the Benq! And now it works...
I suspect that when I upgraded to the new beta NVIDIA 92.91 drivers, something bad happened and it corrupted the Benq.