Hi,

I have an Optiplex 9020 mini tower Intel I7 4770, 8gb ram, AMD 1G HD8490, Samsung EVO 860 500GB, WD400 4tb.

I also have a 1TB drive that is listed as Intel Raid 1 Volume, that was set up like that when I purchased the PC so I know very little about that.

I have been getting the yellow blinking power button for quite a while now, (well over a year), and it has been driving me crazy. I have re-seated the ram and cpu, replaced the cmos battery and keep the inside of the PC clean. I have stripped all the peripherals and tried to start the PC bare and this has work sometimes and not others. I have ordered a replacement PSU and will replace it when it arrives. I never turn the Optiplex off and it re-boots, runs and sleeps and wakes up with no problems at all, which makes me think the motherboard is fine. 

I have found a work around that seems to work every time now. If I push the power button to turn on the PC, nothing will happen until I get the blinking yellow lights. If I disconnect the power lead from the PSU and hold the power button till the blinking stops and then while still holding the button insert the power lead, the Optiplex starts straight away and will run until a power outage or the like flattens the batteries in my UPS.

Is there anyway that the RAID settings or any setting in BIOS could have any effect on the PC starting up?

I hope this gives someone enough information to help with a diagnosis and if the PSU replacement fixes it, I will post the results.

Thanks

Baz