Z170m PRO4S beep codes

The AMI UEFI/BIOS on your board does not have a three long beep code.

If we assume it is a three short beep code, that is a memory problem. Here's a page describing the AMI beep codes:

http://www.bioscentral.com/beepcodes/amibeep.htm

All DDR4 memory will default to a speed of 2133 or even less. The full speed of DDR4 memory that is over 2133 will only be applied with an XMP profile, or a manual setting of the maximum advertised speed.

The only reason you don't see a memory speed of 2666 in the specs of your board (and other Z170 boards) is that speed is based on a BCLK of 133MHz instead of the standard 100MHz. Your board's UEFI will have a 2666 listing if the BCLK is set to Auto in the DRAM Configuration screen.

Is the memory you have one of these models: http://www.gskill.com/en/finder?cat=31&prop_3=2666MHz&prop_4=0&prop_1=0&series=2481&prop_2=16GB+%288GBx2%29&prop_6=Dual+Channel+Kit

If it is, check the QVL list on each of them, you'll find your board on the G.SKILL list. So they should be compatible. If you check the specs, you'll see that the SPD Speed is 2133, the default speed.

You should be using the A2 and B2 slots with two DIMMs, as you have. Have you tried clearing the UEFI/BIOS when you moved the memory around? You should clear the UEFI whenever you change a memory configuration.

You are sure the memory is seated correctly? All to easy to make this mistake.

Have you ever had the board start to the point you can get into the UEFI/BIOS, or install Windows?

One possibility is bent pins in the CPU socket. The only way to check that is remove the CPU.

Sorry but I must ask, do you have a cable from the PSU connected to the 4/8 pin CPU power connector on the board?

Both DIMMs being defective would be unusual, but not impossible. G.SKILL have great customer service, if you need to use a different model of memory, they will likely trade that model for the one you have now. I'm using Trident Z memory in my ASRock Z170 board.

Cicca, can we get your full system specs please. 

Try removing the GPU, clear CMOS and boot with the integrated graphics. Let us know what happens.

I mean remove the ASUS R9 380 Strix from the motherboard. If you did not build the PC yourself or are not comfortable playing with the insides of your case I would recommend you take it to a professional to avoid causing damage to your system unintentionally.

Edited by Xaltar - 26 May 2016 at 3:34pm

The only thing dumb about a question is not asking it, no matter how silly it may seem  It's always better to ask than do it wrong. Make sure you clear CMOS after removing the GPU and before you power the system on.