Haswell H97i-PLUS Big Sur Proof

Got Big Sur installed on my Haswell i5-4570 iGPU-only, Mini-ITX test box (Asus H97i-PLUS mobo). Was unsuccessful on my first attempt a couple of months ago with OC 0.6.4, after which I gave up & installed Catalina.

11.2.1/i5-4570/H97i-PLUS/iMac15,1

But after studying this https://www.reddit.com/r/hackintosh/comments/jw7qf1/haswell_asus_z97_big_sur_update_and_installation/ and other https://www.reddit.com/r/hackintosh/comments/jt5pjx/z97_chipset_haswell_users/ posts about NVRAM issues on Asus Z97 boards affecting Big Sur installs, I d/l OC 0.6.6 & the newest kext set and thought I'd give it another go. Although not being a Windows user, the extraction of the NvramSmi driver from my BIOS was a non-starter for me.

Once again, the install died on the first auto-reboot after beginning the 11.1 install. So I tried adding kexts like CpuTScSync & CtlnaAHCIPort, as well as enabling Dummy Power Management and adding a couple boot-args like -igfxmlr, as well as an SSDT that another user suggested (but which wasn't part of the Dortania Haswell guide), however nothing made a difference. I still got the auto-reboot loop.

Turns out that swapping my BIOS version (I was at 3602) did the trick. I took it down to v.2001. It was a last resort, mainly cuz it's a pain in the butt as my mobo has no BIOS option to save User settings. Meaning I had to go through every configuration option to set everything up the way I had it before. And then do it again after the install completed.

As the screenshot shows, I chose SMBIOS iMac15,1 rather than 14,4 as the guide suggests. Also followed the correct AAPL,platform-id (0x0D220003) and device-id (0x0412) properties for iGPU, detailed therein.

After the install completed, I upgraded to 11.2.1 via System Update, hoping (& fearing) that I wouldn't have to downgrade/upgrade my BIOS again. But the update worked flawlessly without that doomsday scenario.

So this project's done. But I have a couple other older SandyBridge boxes that OC has failed to work on (with High Sierra and/or Sierra). One of them I put Clover and Sierra on. It has a 7-series mobo with i5-2500k and a PNY Quadro 600 dGPU. It's working fine.

The other is a i5-2500K with Gigabyte Z68MX and Gigabyte HD6670 or HD6850 dGPU, neither of which works (all-red screen, or red blocks on screen & constant Finder crashes with IOConsoleUsers/Screenlock error, or a long dump of on-screen hex that ends with a "trying to restart GPU" error. That's happened with both OC & Clover.

Any suggestions for that project would be appreciated. Might be kext-related (?), since none of the AAPL,snb-platform-id/device-id properties I've tried made any difference.

But thanks first and foremost to those who uncovered the NVRAM/Asus 9-series/Big Sur issue & provided me a path by which to solve my installation problem.