Intel Boards sometimes they get peaky regarding USB drives used for Recovery mode.
My experience so far was that low capacity FAT32 USB drives are more "welcome" to flash Intel Desktop Boards.
I am using a 2GB Kingston Drive with no problems so far.
Another point i want to make is, that make sure you don't have any other graphics card installed except the on-board one.
The fact that you don't get a screen it is not always a bad think. Some Intel boards when flashing under recovery mode do not post a screen to see therefore it is advisable to leave it go through for 5-10 mins on its own.
I don't have experience with DQ77CP but my 2 DQ77MK boards they are giving me screens (on both my monitors connected with DVI) after a while during Recovery Mode.....
Maybe another solution would be to reset CMOS and try the whole process from scratch.
PS: another visual indication for Bios Flashing without Screen showing anything, would the blinking Power LED. (At least it does on my own Motherboards).