Question A2/AE and green QLED, cant get to POST no matter what I try

[Matt_138]

Hi, I'm trying to get my old PC to boot but all I can get are error codes A2 most of the time and once got AE then the green QLED is always showing.
I built a new PC which is fine but my old one should be fine as I was using it up until I used my new one, the only thing that I have changed was that I took the M.2 SSD's out of the old one and now I have this error and I'm stuck.
I know what the code means but I don't get why it wont detect my hard drive, I just want to get to bios and install windows on the SATA SSD I have. I should mention that the M.2 had my OS on it
I've tried clearing cmos
Updating BIOS to the newest and even tried 1 before newest
Unplugging everything down to bare components (which started giving me AE but then I pressed clear cmos button and went back to A2)
Tried different ram slots, with 1 ram stick in
I tried without GPU in but because my CPU has no iGPU I wouldn't get any picture anyways and still got the A2 code

Specs:
Motherboard ROG maximus code XI
CPU I9-9900KF
GPU Titan X Maxwell
RAM 16GB HyperX 4000mhz
PSU RM 850w Corsair
SATA SSD Samsung 250GB (This is NOT the M.2 that was in the system before)

Thanks for any help, I need it

 

[Lutfij]

You've posted in the motherboard section but forgot to mention the make and model of the motherboard. Please add that. You might want to retry your CMOS reset option, this time disconnect from the wall and display, then remove the CMOS battery then press and hold down the power button for 30 seconds to drain any residual power on the board. You can replace the CMOS battery after 30 minutes.

As a side note, how did you update the BIOS if you can't get into it? BIOS FlashBack?

 

[Matt_138]

Oh oops my bad, the motherboard is ROG maximus code XI, I'll edit the OP to put it in there too, and okay, I've had the old system completely disconnected from power over night so I'll remove the battery and do that, and yes I used the BIOS flashback to update it

Edit
Okay looks like the PC is displaying BIOS, not sure if it was because of the cmos or because I tried a different monitor, sorry if I had wasted your time on this but I appreciate the help nonetheless