I am having really bad results with Samsung 30NM HYK0 ram. I have this issue with both 2x4 and 4x4 configurations. I have 5 dimms I can test, two sets of matched and one single odd dimm. I have not tried overclocking a single 4gb dimm though. I have tested all 5 dimms separately in another computer with excellent results (Asrock z77e motherboard), 2133 C9 1.4 v and memtest 24 hours pass on every stick. Unfortunately when installed in my GA-Z77X-UD3H, the ram doesn't clock past 2000mhz and doesn't go below cas 10. I can get cas 9 but only at 1333. It doesn't make any sense other than some motherboard setting i am missing. I have tried adding voltage to VTT and to IMC, as well as running voltage from 1.35 to 1.6v. The board will just do a boot loop. It doesn't load the OS. Its not a Windows stability issue, its something about the motherboard and this particular type of ram. I believe the digital read out says 15 then 51 then 15 then turns off. Then it will do the usual boot sequence to Ab (bios). I have tried the F16, F18, and a hacked f20c (i think) bios, the F18 has worked the best so far. With settings: all LLC 3d power control is auto/stock VTT: Auto IMC: Auto Ram mode: Extreme Timing mode: quick. Timing: 2000mhz Timing: 10 10 10 28 Cr 1t everything else stock. DRAM Voltage 1.5 This works. But pretty much any other setting doesn't seem to get past the boot loop besides the stock 1600 c11-11-11-28 Jedec profile. The ram is composed of two sticks from 05/12 batch and two sticks from 16/12 batch. The matched sticks are in the dual channel slots correctly. I have tried changing the order. I can run prime 95 and it has no issues, I can also do XTU memory stress test for a few hours with passes. The thing is, the system kind of acts the way an unstable system would. This was true with both a Xeon 1230v2 and the current 3770k. I have tried it with the 3770k overclocked and stock as well as adding offset voltage to the xeon to see if that would fix it. I tried moving the dimms around physically on the board. I have tried adding VTT and using VTT LLC (which I dont really trust) and ram voltages, etc. Is it because Gigabyte doesn't support the Samsung HYK0? This ram does not have an XMP profile.