The Swamp wrote:
It seems like the 750i chipset is one hot mess. From what I have been able to gather, the culprit in my situation might be the south bridge. People who have been able to successfully do what I'm trying to do have reported that speeds are not much better even with a SATA card. For some reason, the 750 doesn't like SSDs. I don't think there is a workaround. The fact that Nvidia got out of the chipset business tells me they just wanted to wash their hands of the entire thing.
Here is something to check -- from personal experience. Check that the card is well seated in the slot. Because the card edge is physically shorter than the slot, it isn't as mechanically stable. I have a USB3 card, that is a x1, installed in a x16 slot. Because of the slight variation in tolerances between the motherboard and case, if I am not careful how I tighten the bracket retaining screw, it can be angled slightly and in such a way as to prevent the system from recognize it. It isn't readily visible in a cursory visual inspection and took me the better part of an hour to figure out. You might try removing the bracket retaining screw and ensuring the card is exactly vertical and completely seated.
If the mechanical stuff doesn't pan out, I don't know if you have any experience with Linux, but if you do, it would certainly be worth booting off a Live CD. Linux has a few utilities that will give you a very detailed look at what the system sees on the PCIe bus. Plus, the boot log provides very detailed information on PCIe initialization. Further, it will, on occasion, handle cards that the system BIOS can't. I would expect Windows to rescan the PCIe bus and not rely on BIOS initialization as well, but sometimes Windows does silly things.
Even if you don't have Linux experience, if you want to put in the time, I'm happy to help you through the process.