I have have a funky issue and looking for some input from the community. 
 
Issue: The computer will randomly lockup in Windows, when I reboot I get post code 55 (memory not installed). I have to reset the BIOS to get the computer to boot back up. At times it will take 2 or 3 attempts of bios reset to get the computer to boot. I have also gotten this error when I turn on the computer, and always if the computer is completely powered down. This is my 2nd MoBo and completely swapped out the memory, even changing manufactures. Taking a shot in the dark I swapped out the case, and also changed out the power supply. I have tried on 2 different revisions of the bios with the same result. The performance also feel sluggish. 
 
Build: EVGA Z170 Classified K (Bios 1.03)
          Intel I5-6600k
          EVGA GeForce GTX 970
         Corsair Dominator Platinum Series 16GB (4 x 4GB) CMD16GX4M4B3000C15
          EVGA SuperNOVA 850 P2 80+ Platium 850W
          Intel I5-6600k
 
Happy to take any suggestions.  

What hard drive do you have? Also, what if you run 1 stick of memory. Does the same thing happen?

I am running Samsung SSDs, 850 PRO x 3. Yes the same thing is happening with a single stick of memory. 

Did you try each stick one at a time individually? Did you try different slots on the board with just 1 stick?  Could the CPU have a bad IMC?

This really is just questions.  What does BIOS show for the memory if and when you get into it?  Also did you check for bent pins on the cpu / socket.  Is the Cpu too tight on MOB? 

I would recommend first trying the BIOS update I just posted (within the last 5 minutes) among other things it helps with Memory compatibility.  Also, once that is done make sure to double check what XMP says in the BIOS versus what the memory states on the sticker.  Make sure the values are showing up correctly there.
 
BTW, welcome to the forums :)

Just a quick update. I tested the IMC with the Intel CPU testing software. I did a test and the 2 hour burn in test. Everything has passed. I am running the latest BIOS as well. 
 
Later this evening I will check what the XMP says and also pull the CPU to check for damage and re-seat it as well. Thanks for the advise, keep it coming. I will post updates later this evening or tomorrow. 

I see this is a old thread, but i think i might be having similar ordeal. I keep on getting massive freezes at weird point, and just now i see my memory is almost at 100% (2x8gb). I have yet to change the memory out or anything, im just hoping im missing something.
 
It really seems to die when im downloading any games on steam.

micwithoutthek
I keep on getting massive freezes at weird point, and just now i see my memory is almost at 100% (2x8gb).

If you notice the freezing happening when your memory is maxed out, it sounds to me like a software issue. As soon as your ram gets near full, Windows will try to swap memory to the page file on the hard disk, thus locking up your computer. Can you determine which process is eating all your memory? There is no reason you should be maxing out 16 GB.

So my issue turned out to be incompatible memory. The memory was listed as compatible on both Corsair and EVGA sites but after extensive testing, I finally swapped out to memory recommended from the community. So far so good.