GA-Z170XP-SLI - Constantly switching from one BIOS to the other (Dual BIOS)

[erwin34]

Hello, after some hours of nailing down what was initially a freeze on return from Sleep or Hibernate problem about 80% of the time (whichever the OS, WIN10 or Linux ..), I found out that since the beginning my motherboard is in fact switching from one BIOS to the other = Main to Backup, or Backup to Main, 80% of the time, and only at power on.

For the sake of investigation, I made the following experiment:
- Nothing plugged in my GA-Z170XP-SLI motherboard = no disk, no DVD, no extension card, no graphic card
- Just my Intel i5 6500, a PS/2 keyboard and my RAM, 2 x 8 GB DDR4 2133 MHz - PNY Anarchy
- BIOS Version is F6 (latest)
- Clear CMOS by removing the battery (or pin shortage, same effect of course)

- Power ON, get the message that CMOS was cleared.
- This goes to the BIOS settings panel directly since nothing to boot from
- In settings, set Optimized defaults (F7), save to profile named "BIOS 1"
- Reboot ... still seing "BIOS 1" as listed in the Load profile possibilities
- Stays like that whatever the number of reboots

- Power Off
- Power On
- ... no more entry in NVRAM for the Load profiles !
- In settings, set Optimized defaults (F7) again, but save to profile named "BIOS 2"
- Reboot ... still seing "BIOS 2" as listed in the Load profile possibilities
- Stays like that whatever the number of reboots

- Power Off
- Power On
- .. guesss what ... I see the "BIOS 1" entry in the Load profiles !!

- And so on at each Power Off/On cycle, or about 80% of time in fact (seems to depend, sometimes, works well in a raw, and then 5 minutes later, at every boot it switches the BIOS).

More experiment to confirm
I could of course further verify this by downgrading the BIOS to F5.
I had to flash it twice to see it at each power on.
Else I was seeing F5 one time, and F6 the other one !!
And so the problem occurs in both F5 andf F6 at least.

Other experiments to try finding some cure
I tried raising voltage on the RAM to 1.26 V in case there was something there -> no effect.
Same on processor Core voltage (raising a little to 1.180 V instead of standard 1.165) -> no effect.
I tried decreasing the BCLK to minimum -> no effect.
Tried decreasing only the memory multiplier -> no effect.
Tried with only one RAM DIMM -> no effect, whichever one it is, in whichever slot.


Net is: no cure so far 
So it looks like there is something detected by the BIOS making it switch to the other Flash than last power on cycle.
- However, nothing is signalled by the BIOS, no msg ..
- Everything works fine on this PC, under intense loads or whatever, and for hours
- The CMOS battery is ok since when removing it, the BIOS says things where cleared.
- And by the way, none of the procs for copying one BIOS to another are working:
whether I try the Alt-F10 (or ALT-F12 ...?) proc to get Main BIOS copied to Backup, or the rear button power on with front power button proc to get Backup BIOS copied to BIOS, nothing happens, no copy msg ...


Last, this explain why my Sleep (and Hibernate I suppose) fail:
as I read somewhere else, when going to Sleep, a special "pointer" to a set of actions is stored in NVRAM and RAM to indicate to the BIOS that the computer has to resume from Sleep ... since the other Flash is used after the resume, 80% of the time, this fails miserably with nothing happening = the BIOS knows it was in sleep, tries to execute the recovery pointers but finds nothing and freezes .. and a Reset does nothing of course, it stays frozen ...
I need to power off/on again for things to work again (and since RAM has been lost, there is no Resume, except resume from disk in hybrid mode in Win10).



Any idea ?

- Are there tools to find the internal error the BIOS could see at POST, which would push it to change to the other Flash ?
- Why does it happen only at Power On, and not at normal reboot ?
- Is there a way to disable this automatic Dual flash switching feature in Gigabyte motherboards to stay on the same one that I booted at previous power on ?


Thank for any help, erwin34.

[erwin34]

Hi there, posting the answer, which I found after multiple trials and elimination ..

It turns out the problem was the Power !

I have put my hand on a second instance of that motherboard, and had exact same problems => it was not my motherboard.

I changed the RAM for G-Skill Ripjaws F4-2133C15D-16GVR which are listed as compatible with the Motherboard, and exact same problems => not the RAM
(btw, it is said to be CL15-15-15-35 by the manufacturer and listed as such in the motherboard compatiblity list, but it is reported as CL15-15-15-36 in the BIOS of both motherboards .. don't believe this brings performance noticeably down, but worth noting that G-Skill quality is not that perfect ...)

I tested the CPU with all Intel diagnostics/tests I could, and with Prime 95 torture tests, all was good => probably not the CPU.


Then, I noticed that the BIOS was reporting 12V to be 11.88V .. while under Windows, 12V was reported constantly above 12V ..
And this with both motherboards.
Maybe not the same 12V being reported by BIOS and Windows ??


Anyway, that is about 1% less than specs ... so apparently significant.
Also, when not starting properly, my POST diag card was showing

• sometimes that PCI was not starting (FRAME led error) -> only way to get out was to press POWER ON button for 5 seconds
• and other times the things appeared to stop at memory controller steps -> in such case, the motherboard would auto-reboot within 10s and then all was ok

Therefore, I started to suspect the power ..

I tweaked VCC SA, VCC IO (both related to CPU startup and PCI + memory controller) to set them 1% up. And the same with the DDR4 voltage.

With that, I managed to only have 10% of failures on power-on boots


So next, I replaced my power:

• It was a FSP RAIDER S550 550W 80PLUS Silver
• I replaced it by a Seasonic based power, also 550W, 80PLUS Gold

Result is that now all is working perfectly.
And BIOS is reporting 12V to be 12.04V.

Therefore, my conclusion is that the Z170 Express chipset is very sensitive to Power imperfections 
And also it is to stay away from the FSP RAIDER S550 550W 80PLUS Silver 


Hope that will help others ..  Erwin34

[shadowsports]

You get a thumbs up for solving your own issue.   

That PSU is rated at 42A on a single 12v rail at 504w.  Specs look respectable, active PFC, 80+ silver...  but apparently it isn't stable, or the one you had was older or just plain defective. 

If you plan to install a dedicated GPU, I would suggest 650w or above.  You can get by with a quality lower power PSU,  since your draw under load will not likely go above 500w, but you'll always be close unless you go bigger.  Enjoy your rig.