[SOLVED] Experts Needed - Suddenly slow POST and Boot times - ASUS Z170 Motherboard

Kazin76

Reputable
Jul 7, 2016
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Hello All,

I am of intermediate skill level PC builder and overclocker. My PC specs are:
CPU: 6700K
Mobo: Asus Ranger VIII
Memory: 16 GB Corsair Vengence
Boot Drive: m.2 NVME Samsung 970 (250GB)
GPU: EVGA 1080 Ti FTW3
Cooling Full custom watercooled (hardline)
Keyboard: Corsair K70
OS: Windows 10 Pro

For nearly 6 months since doing the custom loop this has been a fully stable build booting up to Win 10 log in screen in approx 20 secs. Without any changes to anything, as of yesterday (8/2) it now takes 3 mins to either boot to the BIOS or Win 10 screens.

Symptoms:
  • Post Q-Codes cycle quickly when pressing start button however the following happens in order:
  • System hangs on code B4 (USB Hot Plug) for approx 90 secs
  • System hangs on code 92 (PCI Bus Initalization is started) for approx 90 secs prior
After this, code A9 shows if I have been mashing the del button to enter BIOS or code AO shows for Win 10. The respective screens shown on the display.

As a side note to above symptoms I also noted intermittent lag and unresponsive behavior within the BIOS screen menu. I have never seen this before.

I have done the following trouble-shooting.
  • Unplugged all USB devices
  • Cleared CMOS (reset to default settings)
  • Reflashed BIOS (3802 current)
  • Changed polling switch on the K70 (tried all settings)
  • Tried different USB ports for keyboard and mouse
  • Changed CMOS Battery ( i read this on the forum somewhere it may contribute)
  • Swapped to igx (intergrated graphics on CPU) and connected HDMI off the Mobo. Disconnected display port from GPU (read this on the forum somewhere)
  • Swapped out keyboard and mouse to a basic type (read this on the forum somewhere)
The BIOS lag still occurs intermittently regardless of above. As the default settings in the BIOS appear to have no improvement i set the following:

  • XMP enabled
  • Fast boot enabled
  • MRC enabled
  • Post Delay time 0 secs
  • Boot device control UEFI only
I have also checked and no Win 10 updates have been installed for nearly a week prior the above symptoms occurring. Last one was a Intel driver 10 days previously and have used my device every day since.

I would very much appreciate any assistance from the community.
Regards
Kaz
 

Kazin76

Reputable
Jul 7, 2016
8
1
4,525
2
Hi All,

In case this helps someone I determined the problem to be linked with which USB devices were plugged into each USB socket on the back of the Mobo. I have no idea why this occurs but I suspect it could be a bios bug. The solution found by accident is if I swapped my keyboard and mouse over to different USB ports a normal boot would occur. Some trail and error was required as this would also occur with some of my other devices, e.g printer, ups communication cable, even a certain USB stick drive triggered it. Have had to now record which go where to help keep a record.
Regards
Kaz
 

Kazin76

Reputable
Jul 7, 2016
8
1
4,525
2
Hi All,

In case this helps someone I determined the problem to be linked with which USB devices were plugged into each USB socket on the back of the Mobo. I have no idea why this occurs but I suspect it could be a bios bug. The solution found by accident is if I swapped my keyboard and mouse over to different USB ports a normal boot would occur. Some trail and error was required as this would also occur with some of my other devices, e.g printer, ups communication cable, even a certain USB stick drive triggered it. Have had to now record which go where to help keep a record.
Regards
Kaz
 

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