Question HDD makes the PC slower ?

May 19, 2021

I have a BIOSTAR S120L SSD 480gb in my computer. Today i bought SEAGATE Barracuda Guardian ST1000DM010 1TB HDD and i installed it in my computer normally as every HDD, connected the SATA3 with the motherboard and Power Supply with the HDD. But when i boot up my computer i am stuck on the boot screen with hotkeys (like press DEL to get in the BIOS, etc...) and in the right down corner it would say A2. But when i got out the HDD from the computer and let it boot from SSD as normal and it would say 99 instead of A2, and boots the system normally.

I searched the A2 error and it says it's because there's no valid boot order, but when i go to BIOS my boot order is on my SSD which is where the system is installed. Then i tried to change the HDD from AHCI to IDE but the only option is to change it from AHCI to RAID, also i tried using other SATA cables and Power Supply ports. And trying to boot up computer without the SSD but the same error occurs. Also i would like to mention when the HDD is in the computer it would take 2 minutes (not immediately like with SSD only) after clicking DEL to get into BIOS from the boot up screen like its very slow, but then in BIOS everything works normal.

After i got finally into system i opened Device Manager and below the SSD model name it appears that HDD's labeled like the Unknown Device and after a quite of time it disappears from the Device Manager. So is there any other suggestions that might fix the problem. I contacted the shop and i was about to go return it for a newer (hope working) one, but i wan't to be sure this one is 100% broken.

Motherboard: BIOSTAR B450MH
Power Supply: idk the exact model but i know its 600W
BIOS Mode: Legacy
BIOS Version/Date: American Megatrends Inc. 5.14, 02.01.2021

Thanks in advance!