Problem Booting After Changing UEFI BIOS to Legacy BIOS

[peterd2012]

Acer V7-751, 500G HD, Windows 8.

I changed the BIOS settings from UEFI to Legacy BIOS when I was working on a problem. Now I can't even get into the BIOS (F2) or change the Boot Order (F12). All I get is an error "Operating System not found". I can boot with a Win7, Win8, or Win8,1 DVD. I suppose I could boot with just about anything else bootable as well.

The problem seems to be caused because it's set to Legacy BIOS and Secure Boot Manager as default #1 boot device. Legacy BIOS can't boot a Win8 drive that has been installed under UEFI (Secure Boot). I have to change the BIOS back to EUFI to boot the WIn8 drive, but the only way to change the BIOS is from within Win8. It's a very flawed way of doing things but it's the way it is.

Does anyone have any suggestions that they KNOW work. Please don't Google answers. I've already done that. And please (please) don't tell me to power on and press "F2" (or any other key) to go into BIOS. If I could do that I wouldn't be posting.

Once again, I cannot get into the BIOS without going into Windows first. I cannot load Windows because the install was done under UEFI. I cannot change from Legacy to UEFI because I can't get into the BIOS.

 

[ronintexas]

I keep a couple of spare hard drives around for this reason...If that is the only hard drive you have, to recover the data from the drive you will need another hard drive to recover the system first.

 

[PinchedNerve]

Bios is stored on the Motherboard and has nothing to do with any version of windows, linux, or any other OS and in fact doesn't require any OS at all to enter. There are programs that will allow bios editing to a degree from within an OS but Windows its self is not your problem. Delete is usually the key you need but for Acer it may be F2 and you are supposed to be hitting it during POST, not during windows load or any other time. POST only lasts about 1 to 5 seconds which can also be controlled a lot of times within the Bios. If you've reduced your POST to load time then your F2/Delete key pressing time will be harder to hit.

Win 8 does not control your bios.

Edit: Lastly, for future knowledge. Going from AHCI or "Legecy" boot to UEFI requires a new install and likewise for the reverse. Not sure why you would want to change from UEFI boot anyway.

Edit again: Here is another thread similar to yours with a bios entry issue. http://www.tomshardware.com/forum/81162-35-access-bios-acer-aspire-5720z

 

[peterd2012]

Normally, you'd be right. In this case you're wrong. 🙂

I could tell you I've been accessing BIOSes since IBM XT days, but that would sound liek I'm claiming 30+ years of experience makes me right. Instead I'll just say that I actually know what's happening and you don't. Let's leave it at that.

 

[PinchedNerve]

Bios is controlled by the Motherboard not an OS and I believe you could go as far as to totally disconnecting the HD and enter the bios perfectly fine. Looking on the Acer support site http://www.acer.co.uk/ac/en/GB/content/drivers I can't seem to find a V7-751, googling Acer V7-751 doesn't help either. Perhaps you're incorrect on the model, so I looked at the manual of a V7-581 and it says

"To activate the BIOS utility, press <F2> during the POST while the computer logo is being displayed."

If F2 is being pressed at the correct time and isn't working then chances are the keyboard is either borked in one way or another (like the all or one of the F keys) or its just not initializing fast enough. Try a desktop USB keyboard.

Lastly, if you would like to prove you are correct on Windows 8 controlling this bios, please provide a support link to your V7-751 and screen shot, specifically the section on entering the bios or better yet a link to this Laptops manual. I would love to see this.

Edit: If you've managed to flash your Motherboard with some other bios (no idea what you're calling "legacy bios") then you may be permanently screwed since you've claimed to have already talked to "the computers manufacturer". http://social.technet.microsoft.com/Forums/en-US/ad646576-5a1d-4300-895e-90e764e3a1c9/cannot-access-bios-or-boot-windows-8-after-changing-uefi-bios-to-legacy-bios?forum=w8itproinstall

 

[peterd2012]

The only fix is to flash the BIOS with the same or a newer version. That resets the BIOS to default settings (UEFI BIOS replaces Legacy BIOS).

"Legacy BIOS" is a specific setting in this UEFI BOIS. The fact that you don't know that tells me you don't know what I'm talking about. Regurgitating the contents of online manuals can't replace actual hands on experience. You'll learn that over time. 🙂

 

[Bandham manikanta]

i hve same issue.. unfortunately i changed the legacy boot option to disable... now it is nt shwng bios itself.. when i swtch on the system it is shwng nothng... can u plss help plss... as soon as pssble

 

[Bandham manikanta]

i hve same issue.. unfortunately i changed the legacy boot option to disable... now it is nt shwng bios itself.. when i swtch on the system it is shwng nothng... can u plss help plss... as soon as pssble

 

[Bandham manikanta]

Bios is controlled by the Motherboard not an OS and I believe you could go as far as to totally disconnecting the HD and enter the bios perfectly fine. Looking on the Acer support site http://www.acer.co.uk/ac/en/GB/content/drivers I can't seem to find a V7-751, googling Acer V7-751 doesn't help either. Perhaps you're incorrect on the model, so I looked at the manual of a V7-581 and it says

"To activate the BIOS utility, press <F2> during the POST while the computer logo is being displayed."

If F2 is being pressed at the correct time and isn't working then chances are the keyboard is either borked in one way or another (like the all or one of the F keys) or its just not initializing fast enough. Try a desktop USB keyboard.

Lastly, if you would like to prove you are correct on Windows 8 controlling this bios, please provide a support link to your V7-751 and screen shot, specifically the section on entering the bios or better yet a link to this Laptops manual. I would love to see this.

Edit: If you've managed to flash your Motherboard with some other bios (no idea what you're calling "legacy bios") then you may be permanently screwed since you've claimed to have already talked to "the computers manufacturer". http://social.technet.microsoft.com/Forums/en-US/ad646576-5a1d-4300-895e-90e764e3a1c9/cannot-access-bios-or-boot-windows-8-after-changing-uefi-bios-to-legacy-bios?forum=w8itproinstall

i hve same issue.. unfortunately i changed the legacy boot option to disable... now it is nt shwng bios itself.. when i swtch on the system it is shwng nothng... can u plss help plss... as soon as pssble.. iam nt even gettng bios logo

 

[komfortablynum]

What a TOTAL Nightmare this problem is. THIS FIX WORKS:

Faced this on a Windows8 Acer Aspire v5-57 - once into Legacy it never allowed another entry into BIOS

I tried resetting BIOS using Jumpers on motherboard - nothing (tried many many times)
Considered removing BIOS battery and leaving it over night - but that required a disassembly, so was a last resort choice.

The Solution I used was Booting from a Windows10 Install Disc (I didnt have a Windows8 Disc available and Windows7 install disc would NOT work) - to gain access to Command Prompt (I think that was Repair, Advanced, Command Prompt)

From there I backed my data up to USB and then followed the instructions on:
http://community.acer.com/t5/V-and-VN-Series/No-access-to-BIOS-Aspire-V5-571G/td-p/157643/page/5
(Copied the install files of a [equal or later version] of the correct BIOS Upgrade to a USB stick - then ran those inside Command Prompt - after two restarts the computer was restored)

The very best of luck to anyone facing this - IT IS RECOVERABLE!