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S340-15IWL Can't Legacy Boot from USB

2019-07-15, 23:39 PM

I've searched through the forums and Lenovo's site and can't come up with a working solution for this new notebook:

I have been able to boot a USB that has EFI, but for the life of me I cannot figure out a way to boot from an MBR/legacy USB.

I've spent hours trying.

 

 

I have tried the steps at https://support.lenovo.com/us/en/solutions/ht076905

namely, disabled OS Optimized defaults, then load defaults, but doesn't help - and I'm getting plenty frustrated.

I cannot find anyway to get into the Lenovo setup utility (Rev 5.0) other than letting Win10 boot, then going to settings/recovery/advance options to boot into UEFI Bios.

The Boot Mode always stays at UEFI, with USB Boot enabled, can only boot GPT/EFI USB sticks not MBR/Legacy.

 

What am I doing wrong?

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12 Posts

07-15-2019

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Re: S340-15IWL Can't Legacy Boot from USB

2019-07-17, 19:27 PM

Still looking for an answer....

I'm almost afraid to try the 1 possible solution of changing the disk controller in bios to AHCI as it gives a warning that doing that will make the internal drives inaccessible and require re-install of OS.... If I don't get any answer I might try it anyway as I can always return this machine to Costco - it's brand new. I guess I could remove the internal drive and try as well....  Not a fan of Lenovo's BIOS interface, Dell does much much much better in that regard.

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09-02-2019

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Re: S340-15IWL Can't Legacy Boot from USB

2019-09-02, 1:02 AM

The UEFI boot mode cannot be deselected as long as the installed SSD remains using Intel RST mode (aka fake RAID). You need to switch that to ACHI mode. But before you do that you better enable safemode in Windows10 (if you care about existing windows install).

 

Essentially in Windows10

Follow below steps to enable Safemode

WindowsKey+R

msconfig

select Boot (tab)

Under Boot options select

Safeboot & minimal

 

 

Now reboot and make sure you are getting into windows safe boot mode

 

Reboot again and get to BIOS. (F2 key)

Go to tab "Configuration" and Under "Storage" switch the mode to ACHI

 

It will warn you something like "all existing data stored on the drives will be erased when resetting controller mode"

 

You can ignore that, it wont do a format or erase or anything.

Reboot again to windows and run the same msconfig and deselect safemode, and make sure everything reboots properly.

 

You can go to BIOS again and you will see that you can now disable UEFI, and play with that setting.

 

 

0 person found this solution to be helpful.

This helped me too

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09-02-2019

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Re: S340-15IWL Can't Legacy Boot from USB

2019-09-02, 1:24 AM

See my last answer. The warning is really to prevent a non-expert user from accidentally switching and then find himself unable to boot into windows. If you follow the proper steps you can switch to ACHI without loosing existing Windows10. And yes switching to ACHI is need to enable legacy boot.

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Re: S340-15IWL Can't Legacy Boot from USB

2019-09-02, 22:27 PM

THANK YOU very much for your reply!

That did the trick for me - except I could not get the computer to boot into the BIOS with F2. Or F1. Or F12. Or ESC - although I think there probably is a hotkey, I just couldn't find it. (If memory serves, might require pressing FN+F-something, but FN+F2 didn't work either.)

Finally, frustrated, I found a pdf manual for this S340 Ideapad which shows there is a pinhole on the side just to the left of the multimedia card reader slot that's designated as the way to get into BIOS (or System Recovery). What a pain as ned a paper clip or some tool to do it, but that does turn the machine on and allows for getting into the BIOS. 

 

In the end, I followed your sequence of changing Windows to boot to safe mode, verified it, then went into BIOS and changed storage to AHCI, booted back to Windows and changed back to normal boot. No data loss, and able to legacy boot!!! Yay!

 

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