You may try connecting the SSD to a different SATA port, and using different data and power cables.
If the system is still taking too long to complete POST, or to enter the BIOS setup, it would be good to remove the CMOS battery to reset the BIOS.
Yeah, I have 6 different SATA 3 ports, and 3 SATA 3 data cables. Been switching them all night long. It didn't help. I'll try reseting the BIOS via CMOS battery, but I'm not that confident it'll work, since I'm using my remaining HDD, and it works smooth and well. Thanks for your reply, though.
We should also take a look at the SMART Details for the SSD, you can get this information using Intel® SSD Toolbox.
Please check the SMART counters and post a picture if possible.
It seems that reseting the BIOS by removing the CMOS battery made it show again in BIOS. Still, I'm taking my hardware to the service for a clearer verification.