@ProStock :
Hy,
i have installed Windows 10 pro 64bit at first try. My MB is MAXIMUS VI EXTREME… I dont have disabled CSM!
Sorry Fernando, was wondering whats the difference between CSM enabled and disabled. I still don’t understand. I have a z87 motherboard and if i turn it to disabled can i boot for a samsung 970 Pro possibly?
You said to another user that CSM can cause stability issues during boot but not during work. I’ve already inserted the latest EFI module you have listed.
Also am i able to choose to use a intel optane ssd 900P Optane AIC by any chance or is that something only newer boards are capable of?
EDIT by Fernando: Cited text set into the correct quote format and moved to the beginning
If CSM has been set to DISABLED withi the BIOS, only EFI modules (and no Option ROM ones) will be be loaded while booting.
You only will be able to properly boot into your OS, if all EFI BIOS modules, which are required to be loaded while booting, are present within your currently flashed BIOS.
Example: If the BIOS should not contain a Video EFI “GopDriver” for your graphics adapter, you can boot, but will just see a black screen.
Okay, thanks. its weird but i’ve looked in my UEFI settings and can’t find CSM feature anywhere on there. I then changed to classic mode to the old BIOS loadout and i see settings with setting things only through legacy/UEFI, both on, UEFI/Legacy only or whichever first or so on. Tried messing with some and it cause me not to be able to load my OS afterwards so i changed it back. Messed with it a bit but no problems.
Hi Fernando!
Using first page guide, I was able to modify BiOS of my GA-Z77X-UD4H (7-Series, no M.2 slot) mobo and use my installation of W7x64 with Samsung EVO960.
Works like sharm, thank you!
I would like to ask, if is also possible some-how to modify BiOS to boot from PCIEX in legacy/NonUEFI MBR mode?
I have some reasons for booting that way. But now, when I press F12 for boot override, my Samsung is detected as "PATA SS" and dont want to boot. (In UEFI mode, it is detected correctly showing full name).
Thanks for answer…
@lime :
Your last post is not easy to understand.
Can you boot off your NVMe SSD?
What is your problem?
@iX-9 :
Only a very few NVMe SSDs are bootable in LEGACY mode using the MBR partition table.
Sorry, i don’t have an NVMe SSD yet, i was asking questions about it the previous post before. I was just curious because i was playing with my UEFI and went to classic BIOS and went playing around to change settings and it didn’t allow the SSD to show up afterwards. I’ve read couple posts from you all over Win-Raid and its not a problem its more of i was seeing if i can disable CSM but since i can’t find it anywhere in the UEFI/classic BIOS i’m stumped. Probably best just to leave it alone till i buy a NVMe SSD. Thanks again.
@lime - On G1 Sniper M5 CSM setting is on the "BIOS Features" page/section, right under the VT-D and Win8 Features setting, see below.
You may need to select “Other OS” instead of Win8, and reboot back to see CSM option, I can’t remember.
I know some option is hidden unless you select Win8 too, secure boot and maybe another too…
@lime :
Thanks for the clarification.
To be able to see the NVMe SSD within the BIOS (as “PATA_SS”), the related SSD has to be inserted into a matching PCIe slot.
Actually, with my new “GB X470 Gaming 7 WiFi” mobo I am able to boot EVO960 in Legacy/MBR mode, just turn off UEFI in BiOS! (Even with Default BIOS settings [UEFI on] - just press F12 and select Non-Efi row of 960EVO.)
So, if 960EVO is that “very few” SSD, should be legacy bootable in old system?
I really doubt it.
AFAIK only the much older Samsung 950 Pro has an NVMe Option ROM, which allows booting in LEGACY mode. I have no idea why you were able to do it with a Samsung 960 EVO SSD.
Was tinkering with the BIOS this whole time after replying back. Literally found where CSM was hidden in, it was in the OS section, had to change from "Other OS" to Windows 8 or windows 8 WHQL to show up. I’m using win 10. If i use a samsung 970 pro, from the clarification
"Note: Some NVMe SSDs like Samsung’s 950 Pro SSD are natively bootable in LEGACY mode (CSM and loading of Option ROMs has to be enabled within the BIOS), because their Controller chip contains its own NVMe supporting Option ROM module.
Enter the BIOS and navigate to the "BOOT" section and - if applicable - the "SECURITY" or "Keys" section.
Make sure, that the "Secure Boot" and "Fast Boot" options are disabled. The "Compatibility Support Module" (CSM) should be set to "Disabled" as well (requires full UEFI compatibility of the graphics adapter) or to "Enabled" with the ability/preference to load EFI BIOS modules for the Storage Disk Drives."
Sorry again, I’m like literally lost because i feel like this contradicts what you wrote… CSM needs to be enabled right for samsungs NVMe ssds to work correct? but if the 2nd section says to set it to disabled… or was it to ENABLED, like i said before. I just want to reiterate that i have loaded the EFI module into the BIOS file so essentially, all i have to do is obtain the NVMe SSD and set BIOS settings, SECURE BOOT AND FAST BOOT to DISABLED and CSM to ENABLED and LEGACY OpRom enabled too right?
Sorry. I’m literally a guy that has hard time understanding. Too little foundation in this type of stuff.
@Lost_N_BIOS :
oh wow, you seem to of had this board possibly? I had the setting set before on “OTHER OS”, when i went to win8 or win8 WHQL it shows up. Thanks, so what do think settings i should change to make sure its on point or optimal for it to be able to boot 100% for a samsung 970 pro NVMe ssd, CSM enabled, Legacy OpRom enabled, Secure boot disabled and fast boot disabled?
I don’t have that board, but had similar G1 Sniper H6 and one of the X58 Snipers too, and knew BIOS was similar. I’m very familiar with BIOS editing, so I looked it up for you real quick when I noticed your question about it.
As for what’s best choice for you, I am not one to comment on that, that’s better left up to the other pro’s here who know best. If you ever need updated modified BIOS, let me know 
I can help with that 
I confirm 960 Evo (mine have latest firmware) work on legacy mode, i test it on a Panasonic CF-19 Mk2 Thougbook : No problem.
Thanks for confirmation! Maybe Fernando comes to believe… 
Now just make it work with old GIGABYTE GA-Z77X-UD4H…
Sorry again, thanks to you Lost_N_BIOS and Fernando for the help, i was reading up on stuff throughout this page and couple others for other modifications and was looking up terms like “GPT, UEFI, and so forth” found in order to boot my 840 Pro in UEFI, change how my partitions were, obviously back then it was MBR, so i found a article and use admin command prompt and inserted 2 copies and paste commands and boom voila, all i had to do was next check to see if it would boot afterwards and it did. I did went to the UEFI and changed CSM from Always to Never, there is no DISABLED feature. Here are my settings down below.
I noticed couple things…
1. The OS loads from the Gigabyte main screen now with a loading sign rather than after the Gigabyte main screen → Windows Logo and loading sign.
2. It is like 1.5-3 seconds faster loading now and i don’t see a blue screen while restarting PC :D, its just complete black and goes to a screen for my system password for my motherboard i set.
3. There is now a drive E:/ shared with my Samsung 840 Pro for reserved with close to 500MB space empty.
What i did for the reserved drive was i went to disk management and right click Change Drive Letter and Paths… and then press Remove button and Press yes. From what it said for removing the drive, it just takes out the letter but i guess it places the partition in the C:/ drive somewhere i guess. Bwam, voila, reserve space is gone, back to my Good Ole’ 2 drives and i rechecked my UEFI settings and checked that it will still booted after restarting. It did.
Only thing left i don’t understand is Samsung SSD’s require the use of CSM enabled? Intel says for their 900P instruction installation, they don’t require anything much for windows 8.1, 10 but for windows 7 however it requires CSM enabled.
With some mainboards and their hardware configuration it is easier to get the NVe SSD bootable after having ENABLED the “Compatibility Support Module”, but this BIOS setting is not really required, if all needed EFI DXE Drivers are present within the currently flashed BIOS.
Little digging in a BIOS of new Gigabyte AORUS Gaming 7, witch is able to boot Samsung EVO960 in LEGACY mode: there is no NVME_Expres_DXE, BUT these: NvmeInt13, NvmeDynamicSetup, Nvme, NvmeSmm.
What if I put these into 7-series BIOS (or just some of them), instead of Nvme_Express ??
I believe, NvmeInt13 has something to do with Legacy boot…