Z87M: very slow boot, but RESET is fast

djc wrote: This is peculiar. My Z87M used to boot just fine, but for some time now, I forget how long, it sits a long time in the BIOS boot screen (sometimes at least 2 minutes). But if I press RESET during this delay, it boots the OS after 2-3 seconds. All the components are properly seated and individually test okay. Windows 7 shows no unusual errors in operation and no intermittent glitches. Nothing looks wrong in the Device Manager or in HWiNFO64. It's a vanilla system: Z87M not overclocked (BIOS P2.20), Intel i7-4790 (stepping C0), Kingston KHX1600C10D3/8G x 2, SanDisk SDSSDX240GG25, WD WD30EZRX, USB keyboard, Logitech USB wireless receiver+mouse, Netgear RangeMax WN111v2 (yeah, I know -- old!). What stands out to me is that when I press RESET the BIOS boots into the OS almost immediately, and otherwise it just... sits. For minutes. Any thoughts?

In other words, from a cold start, shutdown state, the PC sits in the POST screen for quite a while, but pressing Reset causes it to start Windows quickly, correct?

Are you turning off the AC power to the PC when you shut it down, and turn it on just before you start the PC?

ASRock made at least three "Z87M..." board models, so we don't know exactly which board you are using. The Z87M OC Formula is the only one I see that has a Dr Debug POST code display. If you had that board, you could check which POST code the system is possibly stopping or delaying on.

That could simply be the HDD taking a long time to get started, which a Reset allows it to work for some reason. Try removing the Netgear wireless USB adapter as a test, or other USB or other connected components as a test.

If you see nothing in the Windows 7 logs, it seems the PC never gets to the point that Windows is booting, and is not the cause of the initial delay, correct?

I just tried some very simple stuff, with simple results, after the system had been up (sometimes asleep) for about 3 hours. First I rebooted from Windows "Restart", and from POST screen to OS boot took about 22 seconds.

Then I immediately rebooted the same way, and this time from POST screen to OS boot was 7 seconds.

I immediately rebooted, but this time at the POST screen I pressed RESET, and from the next POST screen to OS boot was 3 seconds.

Now I shut down the system and removed the power cord, let it quiesce for a minute, then restored electricity and booted. From the POST screen to OS boot took 4 seconds.

I really don't understand this.