According to Sybausa, the SY-PEX40032 is not bootable.
The transfer speed of a PCI-Express 1.x slot will limit most benefits of using a SATA 3 drive.
The PCIe 2.0 standard doubles the transfer rate compared with PCIe 1.0 to 5 GT/s and the per-lane throughput rises from 250 MB/s to 500 MB/s.
Nails, how do you know that SY-PEX40032 is not bootable?
Could you please give me an example of bootable SATA controller with AHCI support that would work on Intel D915PGN motherboard?