This should be simple: "winload.efi missing or corrupt" yet neither. Win8.1 not booting

I have a desktop PC that was running Windows 8.0 from a slow HDD. I unplugged the old drive and installed a new SSD and Windows 8.1.

Once I got it running, I unplugged the SSD and plugged the HDD back in to transfer my files & settings. But it won't boot. Instead, I get a message that "winload.efi is missing or corrupt. 0Xc0000225". To get the SSD working, I had to disable "Fast Boot" in the (bare-bones) UEFI bios and force "CSM Support" to "Enabled", but undoing those changes and restoring the BIOS back to it's defaults didn't help.

I checked the drive using a Linux Live boot disk and verified the file is still there, and the chance of it being corrupt is very low since it was booting just fine prior to the upgrade.

I tried my Win8 Rescue Disk (USB). It attempts repairs and fails.

I'm stumped. Online searches for this similar issue are no help.

Setup: ASUS CM1855 PC (AMD 3.3Ghz) with really low-end UEFI bios (few options).

Not sure if this is helpful, but I had bad SATA cable or loose SATA cable connection. My drive is Samsung SSD 840 and apparently its SATA port does not have the holes so cables will not "clip" therefore it can easily loose when you are working in the case and touching cables.

I was experiencing many of these random winload.efi errors but also Event 153 in Event Log (thousands per day), PC was lagging a lot. Samsung Magician benchmark showed poor 76 MB/s read performance. And slow boot as hell.

I replaced the cable, made sure it is connected properly (yeah DUCK TAPE I am looking at you!) and everything is so smooth, no more 153 events anymore and benchmark went up in reading to 540 MB/s. This is not the first time I experienced loose SATA data cable, this port design has a serious issue. I only booted few times, but the error is now gone and boot is much faster. So I believe I fixed both issues at once (slow boot with random blue-screen error, event 153).

More info about error event 153 here, you should also check the Event Log I think:

Event ID 153 and 129 for three month old SSD. Did I buy a faulty SSD?