Gigabyte GA-Z170X Gaming 5 EU - Cold Boot Problem

[wiggly1uk2000]

I've joined the forum in the hope of finding some helpful experts. I've been building computers for most of my adult life (I'm now in my mid-forties) but this problem has me stumped...

New build consists of the following:

Gigabyte GA-Z170X Gaming 5 EU
Intel i7 6700 (non-K version)
Corsair 16GB DDR4 (2 x 8GB)
Corsair RM650x PSU
Samsung 950 Pro 256GB M.2 SSD
Sapphire Nitro R9 380 4GB Radeon GPU
Windows 10 Pro (x64)
Seagate 2TB SATA HDD (for data storage)

It's been installed in UEFI mode with GPT. Everything works well and boot times are fine but there's one problem...

From a cold boot the PC switches off a second or two after switch on and then restarts. From the restart it boots and runs normally every time. A warm restart does not make the PC switch off and on again, it's only from a cold start that this happens.

Looking at the PC when this happens, all lights switch off as does the motherboard's LED error readout. As well as adding a couple of seconds to the boot time (from cold) it also puts added wear and tear on my poor Seagate HDD which powers on, off and on again within the space of a few seconds.

To clarify, this issue occurs only from a cold boot and always within a second or two, well before Windows starts loading.

I've used both the F4 and F5e (beta) BIOS and get the same results with both. My gut tells me this is something to do with the Samsung 950 M.2 SSD but I'm hoping somebody else may have encountered this issue and can save me some time and trouble! Will upload a YouTube video if necessary so you can all see what's happening.

Any ideas?

Quick edit... Everything is at stock speeds and the memory is set to its XMP profile. The problem still exists with XMP disabled.

[wiggly1uk2000]

A quick update for those with the same problem...

I decided to remove all peripherals and test the motherboard with just CPU, RAM, keyboard and mouse (via the integrated GPU). The problem was still there.

In a previous conversation with Gigabyte support (for another issue) they advised me to use the Load Optimized Defaults option after flashing the BIOS. I thought I'd give it a go in case something in my BIOS settings was causing the problem. Sadly it made no difference.

Finally I decided to reset the CMOS altogether (via the motherboard jumper) and start again from scratch. After the reset I loaded the Optimized Defaults and then set about configuring the BIOS for my own needs. Bingo! The problem vanished and has not returned even after making numerous changes to the BIOS settings.

As a final test I put back all the peripherals, loaded Windows and then did a shutdown. I isolated the PC from the mains and waited a minute before trying a cold boot (with fingers crossed). Success! It booted correctly and rather quicker too.

Had I reset the CMOS before using the motherboard for the very first time then perhaps I might have avoided this problem altogether. It's just not something I've ever had to do before with a new board. Hopefully that's the end of the matter but I think I'll give it a week or two before jumping to any definite conclusions.

It would be nice if Gigabyte would release a decent BIOS guide for these Z170 boards that gets updated with each new BIOS release. With the F5e BIOS I'm seeing options that didn't exist in earlier versions and it's not always obvious exactly what they're for!

[dmdilks]

That is the problem with updating the bios. See I'm old school and after I do a update I always shut it down. I pull the battery and jump out the cmos pins. Let it sit for 5 mins and then put the battery back in up-jump pins and then set it to optimized default setting.

I have been updating bios for over 20 yrs and only had one fail. Been doing it that way from the start and will do it that for ever. At one time they use to have info on how to do it.

By what I just read what you said about support to just tell you to do a optimized default reset. They have no clue either on how to do it right. So you just learn something didn't you.

[wiggly1uk2000]

The main thing I've learned is that it's worth following the CMOS reset procedure on a brand new motherboard, even if you haven't flashed the BIOS. My problems started from the first day the board was installed that's why I tried the later BIOS versions. Had everything worked perfectly from the start I might well have left it that way and waited until there was a compelling reason to flash it - like the upcoming Skylake bug fix.

I've done CMOS resets many times, just like yourself, but I've never needed to do it on a new board fresh out of the box. Anyway, I'm just glad it's sorted now.