Boot takes too long

[barbaros]

I have Asus Z97 deluxe 3.1 motherboard with 2x8gb hyper fury x ram and i7 4790k cpu, I also have gtx 980 gpu. I have Samsung 850 Evo and WD Blue 1 TB HDD

When I boot up the computer after a long time (like next morning from previous night), Asus logo appears, it says press f2 etc. then just Asus logo waits in the screen for almost 30 secs. After that time white dots turn around like it continues to boot normally. If I restart the computer after this long boot, it just loads up fastly. Sometimes this problem doesn't happen and it just boots in 5 secs.

I checked the digital screen on mobo and it shows B1 on the screen while it waits. And after that it turns to 00 when boot continues as normal.

What can be the cause of this weird issue?

[InfernoStorm]

Have you tried disabling quick boot or whatever the equivalent in BIOS? Some BIOS also allow you to set the boot time, try changing to greater than 5 seconds. I think it didn't properly initialize the SSD because the detection time was too short.

Happened to my older Sandisk SSD and I had to do that in order for it to be detected each time.