The most important piece of information is missing in case of this particular motherboard:
What is the BIOS revision of your board?
If it is 035 or later you are "doomed". Rev.035, 036 and 037 have plenty of memory stability/ configuration problems.
Well done to downgrade the bios? How is done?
Hello again, I have Gskill F3-1600C9D-8GAB. Once I write here as a result.
You can only downgrade to 035 or 036. The problem now is that all these "ivy bridge" BIOSes are complete junk.
You wont get your memory to work perfectly before Intel releases a proper BIOS for this forsaken board.
There is a very long thread here called "Still no fixed BIOS for DZ68BC". You can find what kind of memory configuration problems people are having with this setup.
UPDATE
I have done some work with my test bench regarding DZ68BC:
With following BIOS 035,036 and 037.
All stability / configuration problems seems to be RAM related.
I ran several tests with different configs.
Stability issues occured only with higher speeds than 1333MHZ. I had no problems to raise CPU clocks. If I loaded XMP profiles and ran
memory demanding tests -> BSOD/errors.
Intel Management Engine seems to be out of order as well.
Unfortunately, the brand did not work Gskill memory
. Very, very big company like Intel needs to find a solution to this problem
.
"PQI 1333 mhz 2 * 2GB", "Kingston 2 * 4GB of 1600MHz", "2 * 4GB 1600MHz Corsair," "Ares Gskill 1600" with none of the dual-channel work. Motherboard "RMA" or gone.
My new motherboard was delivered very quickly.There is no problem with version 028 BIOS.Thank you very much INTEL.
Try running it at 1600Mhz@1.5 volts.The xms3 runs at 1.65v by default on xmp profile.
Hey guyz! so, i had the same problem with ma MB, i installed BIOS version 39, but when i choose the XMP 1600 ram profile the bios dosnt initiate... so i downgraded to 37 and had no problems anymore! u can download the .EXE file v.37 and just execute, and it will install the v37 and u will be able to use ur 1600mhz memories on 1600!!!! cheers 
