Do I boot my SSD into UEFI or P0? What happened to all my files that I moved over to SSD?

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Chokachilds

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Apr 8, 2014
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Here's my situation:

I recently got a SSD. Installed a fresh copy of Windows 10 on it using the Media Creation Tool. When I boot into it, it gave me the option of:

UEFI: Samsung 850 EVO
or
P0: Samsung 850 EVO

I was unsure of what UEFI meant, so I boot into P0. From there I moved my whole Steam folder to D:\. I then read up that I should be booting into UEFI instead. I tried that and immediately saw that none of my Windows preferences were saved nor my SSD showing any signs of me moving my Steam folder over. It only had the Windows 10 installation on there. I then booted back into P0, and saw that Steam did not exist, despite my SSD showing that the space had been used.

Here's a pic: https://gyazo.com/7cca633c188b983905cc599bdb4acf61

The SSD is the one on the right.

I just want some info on what happened, and if there's any way to recover my Steam folder. I only want to use my SSD to store Windows 10 and my Games. Also, I want to know:

1. Should I be booting into UEFI or P0 for my SSD?
2. Why are none of my Windows Preferences set on the UEFI boot, but available on P0 boot?
3. Is there a way to remove Windows 10 from my HDD?

Thanks guys.
 
Solution
Barty1884
You would've had the option, but may have automatically proceeded past it. You need to select the "UEFI - WhateverYourUSBisNamed".

Regardless of what was selected, if C is your HDD (since you haven't reassigned your drive letters), then that's what you've booted from.

Yes, you would need to start again - boot from the USB and select the UEFI option to install to the SSD (disconnect the HDD to avoid any accidents).

I'm not 100% why your Steam folders have disappeared, but I can only assume the UEFI vs Legacy issue is the route cause.

I assume regardless of which boot option you select, your Steam folder remains on the HDD (either C if booting from P0 or D if booting from UEFI)
If that's the case, just leave it alone for now. Once...
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Barty1884

Barty1884

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1. UEFI. P0 would be the 'legacy' option

2. Did you reinstall to enable UEFI? If not, and you simply amended in the BIOS, you shouldn't be able to boot full stop.
It sounds like your W10 was installed with UEFI enabled on the HDD, and when you installed to the SSD you selected P0.
Essentially, what I believe happens here is:
*When you boot with UEFI enabled, it's booting from the HDD.
*When you boot with UEFI disabled, it's booting form the SSD.

You need to configure your BIOS as you want to use it (UEFI enabled, Fastboot on/off etc) BEFORE you install the OS to the drive you want.


3. you cannot remove 'only' the OS install from the HDD. You have to format the drive, removing everything. Disconnect the HDD while you figure it all out, then reconnect and copy your data over. Only once you're 100% sure you've got UEFI setup and booting from the SSD and your data is migrated would I consider formatting the HDD.
 
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Chokachilds

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Apr 8, 2014
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Thanks for the insight. I'm having trouble understanding what you meant in "2.". To add or clarify, I downloaded the Windows Media Creation Tool on a USB stick. Then, unplugged HDD to install Windows 10 on SSD. After that, I replugged my HDD and pressed F12 to boot. I was given 3 options: UEFI: SSD, P0: SSD, and P1: HDD. I chose P0: SSD and proceeded to move my Steam Folder into the SSD.

The next day, I boot into UEFI: SSD instead. This time, the Windows layout was completely different from P0. All the files that I moved into the SSD were missing, so I boot back into P0. However, the files still were missing even though it shows that space is being used up.

Anyways, thanks for the info.
 
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Barty1884

Barty1884

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Something seems amiss there.

When you booted from the USB, you would've been presented with something like:
1. "UEFI - USBDriveName"
2. "P0 - USBDriveName"

If you selected option 1, you installed in UEFI. It would not install the legacy option, it would install in UEFI mode.

Given the screenshot you attached (it won't load for me now), you have a C drive and the D drive was your SSD?
Unless you mapped the drivers and reassigned drive letters, C is your 'boot' drive.
If D is your SSD, C is your HDD. And since C is your HDD and also your 'boot' drive = you booted from the HDD.


When you're selecting "UEFI - SSD" you're booting from the SSD.
When you're selecting "P0", you're actually booting back into your old HDD installed OS. That's why they look different.
 
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Chokachilds

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Apr 8, 2014
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I was never given an option to choose which USB I wanted to boot into. I don't remember exactly, but I let the PC run for a few seconds and it automatically booted into the Media Creation Tool. The screenshot posted was when I booted into P0: SSD. C:\ is my HDD and D:\ is my SSD. I don't know how to map or reassign letters.

So would it be advised for me to format my SSD and reinstall Windows 10 from my USB again except configure options to make sure I install on UEFI? Also, I was wondering if you knew the answer to my issues with my Steam folders disappearing after my boot sequence:

First boot: P0: SSD - Moved Steam folder from C:\ (HDD) to D:\ (SSD)
Second boot: UEFI: SSD - Everything was missing from SSD but this time, C:\ (SSD), D:\ (some 99Mb w/ a upgdrvr file) and E:\ (HDD).
3rd boot: P0: SSD - All steam folders still missing, but the gyazo picture shows that space is being used up.
 
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Barty1884

Barty1884

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Apr 16, 2015
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You would've had the option, but may have automatically proceeded past it. You need to select the "UEFI - WhateverYourUSBisNamed".

Regardless of what was selected, if C is your HDD (since you haven't reassigned your drive letters), then that's what you've booted from.

Yes, you would need to start again - boot from the USB and select the UEFI option to install to the SSD (disconnect the HDD to avoid any accidents).

I'm not 100% why your Steam folders have disappeared, but I can only assume the UEFI vs Legacy issue is the route cause.

I assume regardless of which boot option you select, your Steam folder remains on the HDD (either C if booting from P0 or D if booting from UEFI)
If that's the case, just leave it alone for now. Once your OS is installed with UEFI onto the SSD (C), you can copy them over before formatting the HDD.
 
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Solution
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Chokachilds

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Apr 8, 2014
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Thanks for the reply. That pretty much does it for me. One more question. Can I just unplug my HDD again and boot from USB to install Win 10? Will that overwrite the existing Win 10 on my SSD, or is there a way to wipe my current SSD (Samsung 850 EVO) before I boot into USB? Thanks a ton.
 
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Barty1884

Barty1884

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Yeah - you don't *need* to disconnect the HDD, but it can avoid accidents so is recommended.

Once you boot from the USB, it'll ask where you want to install (and you'll be prompted with your existing partitions).
At that point, you can delete each partition until you only have the one, noted as "unallocated space", and proceed with the install.
 
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Chokachilds

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Do I need to do anything prior to set up my system? You mentioned something about configuring my BIOS. How do I make sure that AHCI is enabled or my BIOS is ready?
 
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Barty1884

Barty1884

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Tough to say 100% without knowing the board you have.

Generally though:
*Fastboot = On
*CSM/Legacy Support = Off
*SATA mode = AHCI

If your board is fairly modern, those should all be active with the "load optimized default" setting -- perhaps excluding CSM/Legacy support which may default as 'on'. Disable that.

Otherwise, there shouldn't be very much to it.
 
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