Flashed 4,1 no longer booting into Windows..ideas please!
Up until the holidays, my early 2009 MP (flashed to 5,1 firmware) also doubled up as a very capable Windows machine, particularly once I got the RX 580 card in. Wolfenstein 2 demo ran very very nicely indeed, and I was going to be gaming a lot more in Boot Camp. The only slight issue was booting from HD, and speed thereof. Like wading through treacle, or molasses for the leftpondians. So, I got a new Crucial MX300 SSD in the sales, put that as new HS boot drive on the PCIe card, putting the existing SSD in a drive bay. I copied my (stable, working…at least before this!) Win10 install from the HD with Winclone (& then erased that HD so there would be no confusion). And…nothing. Whether picking the Windows option from the boot manager, the Startup Disk preference, or BootChamp (yes, SIP is disabled…I did the kext edit hack to get 10.13.2 sleeping OK again with the RX 580, so it has to be)…nothing. It just hangs at the boot menu if I select Windows that way, or with the plain white screen right after boot (at least with monitor plugged into the GT 120) otherwise. Nor will it boot from a Win10 install DVD, Win10 boot USB, or even my retail 8.1 DVD. They just hang the same way.
What I've tried, with both the SSD and the HD…
(Multiple) reinstalls via Winclone of Win10 & 8.1 images.
(Multiple) erases & reformats of the Windows discs via both the Boot Camp Assistant and Disk Utility. Clean install wouldn't work because of the DVDs and USB not working.
Partition table checked (multiple times) with GPT fdisk.
'Make Legacy Bootable' option applied successfully, repeatedly, with Winclone. EFI didn't work either, at risk of stating the obvious.
Moving the drives around the various bays (it was worth a try)
Pulling out and reseating the processor tray (I really did try and think of everything)
Two PRAM resets.
I wasn't convinced Apple's method of resetting the SMC actually did anything- I tried it a few times and the lack of confirmatory chimes doesn't help- so today I pulled the RX 580 out and held the SMC reset button on the motherboard down. No dice.
Zero issues booting into any of the other options (my primary SSD, the HD where my files live, Recovery or Time Machine). Parallels trial version SNAFUd the Boot Camp drive installing its tools, but VMware Fusion did not. And that way, via Fusion, Windows 10 boots just fine. Go figure.
This is annoying rather than exasperating- Windows is a 'nice to have' not essential for me, and it did at least stop me spending some money in the Steam sale- but I can get Windows booting working again that would be great. However, I'm out of ideas......