Memory (2 sticks) should be in slots 1 and 3
not 1 and 2  

Hi phdstudent,
 
please try to populate only slot 1 and clear the cmos before booting.
 
The Debug LED should display the cpu temperature after the system has fully booted into the operationg system. Unfortunatly I don't know what it means if it stopped in code A2 (IDE Detect).

When I install a single memory module in either slot 1 or slot 2, I get code 55 (Memory Not Installed). I get the same code, if I populate slots (1 and 3) or (2 and 4). When I insert a memory module in either 3 or 4, I get IDE Detect but I cannot enter BIOS.
My drive is Samsung 950 Pro M.2. As far as I understand, I need to configure BIOS before I can use it.
The only component that I have not yet replaced is the power supply. Could it be that the 24-pin connector does not supply power to slots 1 and 2?

I removed the motherboard from the case and, first, tested the pins on the 24-pin connector and 8-pin connector using a voltmeter. After this examination, I can conclude that the power supply is in order. After that, I removed the cooler and saw that the thermal paste was not spilled outside of the surface of the processor. I erased the thermal paste and purified the surface of the processor. After removing the processor from the socket, I examined both the pins in the socket and the connectors on the processor. There are absolutely no visible physical damage either to the processor or to the socket. Finally, I re-installed the cooler and made sure that I do not overtighten it. The problem remains the same: memory modules are not reconginzed when inserted into DIMMs A1 or A2.
 
I have no idea what causes this problem, especially, since these are my second processor and motherboard. What I have not yet replaced is memory. Is it possible for memory modules to be defective in such a way that they work in DIMMs B1 and B2 but not A1 and A2? If not, what should I replace first to resolve this issue: the processor, the motherboard, the BIOS chip, the cooler?
 
I hope that you can help me and thank you in advance for your response.

xenolith
I just got a Z170 FTW BIOS 1.03 today and I got the same error:  55 - "no memory installed".  That's why I'm here.
 
I just took out the two sticks of memory - GSkill Ripshaw F4-3200C16D-16GVK - and reseated them and noticed two audible clicks as opposed to one click the first time I installed them.  It booted right up into the BIOS with all the memory detected.
 
After seeing Pgcmoore's post, the question I have is, why does my manual say to install the memory in DIMM slots 2 and 4 as the primary slots?  I have them currently installed in DIMM slots 2 and 4, not 1 and 3.

Go by what your manual says. My Z97 motherboards all specify slots 2 & 4 while my Z77 motherboard stated use slots 1 & 3. Things change with each chipset and motherboard. Always rely on the manual that came with your motherboard.

I conducted one more expriment. With the motherbaord placed on a wooden horizontal surface, I unscrewed the heatsink altogether, so that it rested on the processor on its own weight. The problem remains the same: when I install any of my two 8 GB memory modules in DIMMs A1 or A2, the error code is 55 (Memory Not Installed), but both memory modules work in DIMMs B1 and B2.
 
I double-checked the memory compatibility list for the motherboard, and it turns out that F4-3000C15D-16GVR is not on the list. The closest memory model to mine is F4-3000C15Q-16GRR. I thought that the memory model was on the compatibility list, but, evidently, I confused it with a different motherboard model. Could it be the cause of my problem?

Dear EVGATech_DaveB, I was unable to follow your suggestion of entering BIOS when a memory module is installed in either B1 or B2 because the BIOS does not appear on the screen. I tried simply pressing the Del button but I am unable to get into the BIOS in that way either. All I get, in this case, is a blank screen and code A2 (IDE Detect). Do you know why that is? Perhaps, this circumstance can point to the possible cause of the memory issue.
 
I have already ordered a memory kit that is on the list of compatible memory. If that will not resolve the issue, I will replace first the processor and then, if that does not help, the motherboard. What do you think?

phdstudent, do you solved the problem with Asus Z170?