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Difference between Legacy and UEFI boot modes

MattyB

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Mar 19, 2012
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Hey guys, what would be the major difference between using Legacy and UEFI boot modes?

I updated my BIOS in my ALX and then when it went to reboot, I got some message saying, 'internal hard disk drive not found......and, No bootable Device....' and obviously it wouldn't boot. I went into the boot menu and managed to boot up from my SSD. When I restarted, I got the same error message. When I went it the BIOS I noticed that it was set to UEFI boot. I changed this to Legacy and then everything went back to normal.

Is it supposed to boot using UEFI or Legacy? It's just strange that it defaulted to UEFI when I updated the BIOS.

Any ideas?
 

sway

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Apr 12, 2012
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Wow I just went through hrs if this shit last night, I updated my bios and my comp just fried. I had multiple issues and one was that exact same thing your having after swapping cables and to many other things to list it just starting working.

This bios update this is crazy and I knew what I was doing, im still trying to get my comp back to normal, but I lost everything on my ssd boot drive. The default is uefi boot on mine, make sure when loading a windows dvd for repair or to reinstall, you select the dvd drive without the uefi otherwise it'll cause more problems.

tappin from the aokp running Nexus
 

MattyB

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Well i have left it set to legacy. Seems to be the only thing to make it work. The Dell guy did suggest to disable secure boot. I'll give it a go.
 

sway

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I'm stuck, my HDD that came with the x51 isn't recognized. All I have is the ssd and bios set in legacy, apparently the HDD is in uefi format. Is their a way around that?

tappin on the aokp running Nexus 7
 

MattyB

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No idea. Maybe take the SSD out and just boot from the old HDD. Then go into BIOS and reset it to Legacy. Then replace the SSD. Could work. Probably not since I have no idea what I'm talking about :p

EDIT: So the Dell guy told me that UEFI replaces BIOS. Not sure how or why.....
 

sway

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Yeah its a lot of info, its a more secure partition on the HDD and its really hard to delete it I'm working on it now. Totally redoing my secondary drive too. I've done nothing but HDD stuff all day copying and backing up and formatting...Im freaking tired, my desk broke (don't ask) got another better one, my awesome monitor comes tomorrow and im pretty tired of looking at my comp. After this I'm gonna be set to to legacy only boot, screw uefi.

tappin on the aokp running Nexus 7
 

yikes81

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Feb 13, 2012
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Here is something that I found on UEFI.

In order to install OS in UEFI mode, you have to have a boot device (say, USB stick) which contains UEFI bootloader.

Here is a quick guide for Windows 7: Installing Windows 7 in native EFI mode from USB - bit-tech.net Forums

After you ensure that your boot device has /efi/boot/bootx64.efi file, installation should work without a problem, and any partition size should work (it does not matter at all, actually).

As for the questions about UEFI in general - basically, UEFI is a replacement for BIOS. Without going into technical details, the most important difference is that UEFI is 64-bit, while BIOS works in 16-bit real mode. This adds certain amount of latency in the boot process (and resume from sleep) because your 64-bit processor will simulate 286 CPU from the power on all the way until your OS starts booting, only then your OS will switch it in 64-bit mode.

As you can see, this is a pure waste - however, it took 10 years for UEFI to became remotely popuar in the desktop market, as BIOS kind of "kept up" with all kinds of patches and workarounds to support modern hardware. PC OEMs were reluctant to turn UEFI ON (and they still are, actually) because desktop Windows versions before Vista SP1 did not support UEFI - and this is only for 64-bit. For 32-bit, it took until Windows 7 until UEFI became fully supported in 32-bit Windows.
 

DeRon1

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Oct 5, 2012
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thanks for this information m8...it will come in real handy! I definitely need your help when I add this other HDD to bay #2! don't have a clue what i should have to do on the tech side! I thought it would be easy but i am hearing a lot of conflicting methods! All I wan't is to add an additional 500gig Hdd:D
 

sway

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Apr 12, 2012
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I've tried everything to get this uefi partition off of this hdd that came with the x51. It won't come off, I tried a few programs, diskpart/ clean and clean all commands, if anyone has any solutions please lmk im open. This disk is fixing to be trashed and im going to go pick up a new wd hdd, way to much trouble to format my own hdd. Im not stupid when it comes to computers, but ive been put to the test lately over something ridiculous imo.

Dell isn't any help they want to replace my mb, um ok. For once Google is less help... than even dell. I would hate to spend money on anther hdd but looks like it's the only solution, im tired really.

tappin from the aokp running Nexus
 
Last edited:

MattyB

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Cheers Yikes. That info helped.

Good luck sway. Sounds like frustrating work!
 

sway

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Apr 12, 2012
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Cheers Yikes. That info helped.

Good luck sway. Sounds like frustrating work!

Im trying one last thing, found a program called (bdans boot and nuke), it's got some insane cleaning techniques.

tappin from the aokp running Nexus
 

sway

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Apr 12, 2012
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Ok I fixed the problem, everything is good now. In case anyone is wondering how, I bought a new hdd.

tappin from the aokp running Nexus
 

sway

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Apr 12, 2012
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I couldn't take it anymore, I was ready to game on my brand new monitor, can't install a bunch of games on a small ssd haha.

tappin on the aokp running Nexus 7
 
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