Re. AHCI: Yes, it was the BIOS from #99 with that issue.

Results:
M1.bin retry (in case first attempt was a bad resolder): Ivy endless powercycle (on for 2s, off for 3s) - same result. Did not test Sandy.
BIOS from post #5: please reupload, no longer there
M8IGOPIVB.bin: Sandy PCIE boots, AHCI works, Ivy no boot onboard or PCIE (powers on and sits there, no USB init, no LAN, no HD)
go2.bin: Sandy onboard & PCIE boots, AHCI works, Ivy no boot onboard or PCIE (powers on and sits there, no USB init, no LAN, no HD)

I'd like to test that BIOS from #5.. It's strange that Ivy works on that one for others, I'd really like to try it for myself and see if it works, as it seems to me we're getting stuck before even reaching the vBIOS stage with these. If it does work, it'd make a good baseline.

That's not a good sign! Here is BIOS from #5 again, also updated link on that post.
http://s000.tinyupload.com/index.php?fil...896483348377267

I think the issue may be "Made from dump" vs "Made from stock BIOS" and how it's flashed in. Everyone else here is flashing, and this makes a huge difference when flashing in stock edited vs programming in stock edited.
These are made from stock BIOS, so should really only be flashed in, on top of (Full) BIOS that was not programmed in from a stock BIOS.
Stock BIOS is missing NVRAM volumes and tons of entries inside NVRAM, when you program this in vs flashing you loose everything in NVRAM that was there originally (This is tons of info and settings).
So if these also fail for you, then you need to program back your original BIOS that was dumped first from this system, it needs to have a full non-stock NVRAM volume (Or two).
If you are unsure what this means vs a stock one when looking at NVRAM contents, upload what you think is your very first dump from this system and I will let you know if it's really a dump from non-stock programmed BIOS or actual full dump from the board that's only had BIOS flashed in before (it's a huge difference)
Flashing in now vs dump wont help, unless you first have a complete/full (non stock/empty) NVRAM filled BIOS on the board before flashing.

I see what you mean! I'll have to read through the thread to figure out how to flash from DOS. My original dump (immediately after initial removal without any flash attempts) is in post #91.

I will test the #5 BIOS and see what happens; if it doesn't work, I'll reflash my stock, flash #5 from DOS, and test - if Ivy works, I'll repeat tests with all the other 4MB BIOSes by flashing in DOS.

In the package above in text I described how to flash in the modifications.txt, but yes you may also need to read through the thread because I cannot remember which method ended up working for users earlier.
Thanks, I had not used your dump for any of this, I didn't think about the stock vs dumped actual (NVRAM stuff) until I mentioned above after realizing you had issues with BIOS files that others didn't have issues with.
And yes, I checked your backup, it has dual NVRAM volumes, fully populated as expected. All BIOS I have sent for you here have only one empty stock NVRAM volume, so this is likely the main and huge issue/difference between your testing and others previously who flashed instead of programmed.

Program back in your dump from 91, then retest any/all BIOS via flashing not programming. However, ME flashing will possibly be an issue, especially changing versions like we did . I may need to remake some BIOS for you using your dump instead.
Or you can use this guide to edit your BIOS from 91 before you program it back in, to unlock FD fully, then you can use FPT from ME System Tools V7 package to FPT flash ME8 (ONLY).
Then carry on with rest of BIOS testing by flashing using AFU. Here is command to flash ME region only using FPT >> FPTw.exe -me -f source.bin (For source, you can use any mod BIOS here with ME8, or extract ME region.bin from any mod BIOS here and use that as source)

Don't use FPT/method to flash BIOS or BIOS region, unless it's created from your dump, otherwise you'll have same stock NVRAM issue as with programmer (FPT programs in exactly what you give it, AFU does not and leaves your NVRAM in place).
If you do use FPT to flash in ME8, only use one of the mod BIOS here as source for the ME region, since it contains all the proper settings transferred in already.

OK, sounds good. The steps I took:

1. Modified 260s_stock.bin with the guide mentioned above (FFFF'd the 3 regions to unlock FD)
2. Flashed to chip, soldered, booted, loaded defaults
3. Extracted ME.bin from M8IGOPIVB.bin
4. Loaded to USB along with ME7 tools
5. "fpt -me -f ME.bin" - was successful, verified MEv8 with MEINFO after poweroff, sit for 30s, poweron
6. Used AFUDOS ES 3.06.01 with "afudos M8IGOPIVB.bin /p /b /k"

This resulted in a Sandy boot via onboard and PCIE, but dead on Ivy in both cases.

I will try the same steps but with the BIOS in #5 next. I assume it's OK to flash over the existing one with AFUDOS?

EDIT: Tried this; Sandy boots PCIE, Ivy does not (same as all other attempts).
Tried MS-A10_MEvBIvy2.bin as well out of curiosity, same behaviour - Sandy boots PCIE, Ivy nothing. Keep in mind I did not try onboard for either attempts, though I don't think it'd make a difference.

Onboard may be required, in the sky/kaby/coffee mods they had to create PCIE mod to fix PCIE function, and only in latest BIOS I've created for you past few days has correct GOP modules for Ivy, earlier ones do not have GOP changed only vBIOS (I think)

What is this BIOS M8IGOPIVB << From early on, or one I sent you recently? Either way, once you flash this, you loose all that NVRAM stuff I was discussing when you used all those flags with AFU.
I am not 100% sure, you'll have to test by flashing, dumping, compare with 260s_stock.bin in UEFITool at first volume (NVRAM, expand), but I think only one you want to use is /p - /b is not needed, and /k may overwrite NVRAM (Unsure), but I'm also unsure if /p does that as well.
Before doing anything to try and correct this or redo things, dump current BIOS via FPT and look at the NVRAM volume, is it populated with lots of stuff like 260s_stock.bin, or empty with only 8-12 items like you see in a stock download update BIOS?

Good thing is now you have unlocked FD, so you can re-write 3010 BIOS any time too when you are ready, just be sure any time you flash in a full BIOS (not region) that it also has unlocked FD
If you always make sure FD is unlocked in the file you are about to flash, you'll never have to pop the chip off again.

Maybe @Flagers can also help to speculate why it worked for him but not for you? He could also clarify which method he was using to flash, that might make a difference too if you're using different method now, like other AFU version etc

I would like to use a rx 550 on my dell 620 but for that i would need a uefi bios.
i7 2600 + 0Gdg8y
Sorry for my english (google translator)

@Lost_N_BIOS
When flashed with the 3010(change the 8MB bios chip),it could support ivb and uefi boot mode.But the machine just got 2 sata interfaces available.

For convenience,I think 4MB bios modded is better,and it could flash with software but NOT desolder.

@gloobox - hide the one you don't need, problem solved

@Lost_N_BIOS
Thanks!
I'd got the mobo,and I had programmer.And I 'll tried and give you some pic.And I will going to do more functional test.

@gloobox - Yes, once you get it going, send me pic of the BIOS and circle the setting you need hid, I can hide for you if you aren't sure how

@tiagocx1337
You could mod your vga bios,and disable the uefi boot in your vga bios.I think modding the bios of your mobo is harder than vga bios.

@Lost_N_BIOS
My bad!
I launched it,and it showed "3010" in the left upper corner on the screen interface of the bios .

@Lost_N_BIOS
I found the mobo got was OptiPlex 390 from the tag in mobo,but it's bios chip was changed with the 8MB bios chip.
On the other hand,I could not update any bios version in the official website neither in DOS nor windows.

I met several mobos of dell had the problem,such as 3010.3020.7010,they had a similar place that the bios chip was desoldered and flashed by bios file dumped on other mobo(same model).
I think something in the original bios must have gone?or dell must exam some ID and SN for match?

@gloobox - Dump BIOS for each system, can be FPT or programmer, then look in last volume for FID (Flash ID), make this match the BIOS you want to flash in, this often what allows or blocks flash by applications.
Sometimes though, this info needs edited in more than one place in BIOS.