I received my asrock Z77 extreme 4 yesterday, the board came with bios version 1.20. I first started it with only 1 ram stick out of 4 (got a 4x4 GB corsair vengeance kit, CML16GX3M4A1600C9 listed as compatible on asrock site) no problem. I added the other 3 sticks, rebooted, all nice, windows installed with no issues. Then I saw that a new bios, version 1.50 has been released. I updated the bios (official not modded at this point) via instant flash, with success. But then, the mobo failed to post ! The fans are turning full speed for a few seconds, then the board shutdown and this cycle continue a few times, after that, dr debug show code EE or eventually 20 (not referenced) I first though it was a bad flash, but it was not. After clearing cmos, waiting for condensers to discharge, still a no go, startup / shutdown loop without any post. I then removed the memory, just keept one stick on A0 bank. Here it is ! boot ok ! I then reinstalled all the four ram modules. Fail with startup / shutdown loop again. I added another, stick (in single channel ok). The board refuse all four sticks now ! The problem is that same config was running fine with bios 1.20. The update to 1.50 screwed up my rig ! But I'm not sure that's the 1.50 itself, it may be the 1.30 or 1.40. I suspect something bad was made in 1.40 because changelog indicate "patch G-SKILL F3-17000CL11Q-16GBXL memory". Tonight, I'll test going back to 1.30 and 1.40 to see if it works, if not I'll go for 1.20. Any thoughs or opinions ? Update : I just seen asrock released another new bios today, 1.60. The 1.50 was released yesterday... perhaps they corrected it in a hurry.