power the pc down and unplug it from the wall. pull three of the four dimms out and then use the usb flashback to put all the new bios onto the mb. the stock one was 801 then they came out with a 900 bios a 1012 then a 120x bios. make sure you do them in order from lowest to newest. with a usb stick down load the bios file and unzip it. it be a long names *.cap file. rename the bios file per the z77 renaming guild on asus web page. if it renamed right the flashback led will blick for a few min then shut off. on the new power up it will rebuilt the bios file. after the file is made go into the bios hit f5 and save and exit. after the last file is flashed and the bios defaults are loaded go back into the bios and under the ai tweeker set the bios to use xmp profile.
save and exit and download cpu-z check that the mb and ram are running right and the speed is right under spd tab. turn off pc and depower mb again and move dimm into next slot. do this to test each slot is working. in last slot run memtest86 and see if ram is fine. if it is then add one dimm...walk it ...test it. repeat with dimm 3 and 4. if the ram glitches out with dimm 3 or 4. try upping the dimm voltage...if is still screws up email asus and ram vendor. may be one of the dimm kits that has two or 3 stick ram limit.