Is it bad to switch Boot Mode? (UEFI, Legacy)

I find it interesting how this post gets completely ignored by everyone while older and newer ones get answered. I called Dell Customer Support about this and got no answer of how to get Legacy Mode working again.

This is insane. I follow instructions to download the new bios version which is recommended, and then it breaks my PC basically, and no no one is answering my question. 

1. I recently made the dumb mistake of updating my bios from like bios 5 to 12 since i'm getting a new graphics card soon and heard that you have to update the bios first.   2. As expected, it went wrong, and it crashed during the reboot and all day have been stuck at a black screen when starting my PC saying to choose boot priority or something.   3. Finally, as I was trying everything to do in the F12 menu, I decided to switch the boot mode to UEFI from Legacy. It actually booted after doing that, and luckily my hard drive is intact, but there were some interesting things I noticed.   4. First of all, the space of my HDD seemed to decrease slightly as I realized when going to my PC.   5. Second, there was some weird stuff with Alien Autopsy (not really sure what, but it brought up an error message).   6. Also it might be running a tiny bit slower. Hard to tell. It boots slower as well.   7. So, is changing the boot settings dangerous, or did I do the right thing? Or did I just ruin my PC today?   I have an Alienware Aurora R4 running on Windows 7.

Alright thanks, i'm just going to keep it at UEFI. I heard that Bios 11 only works with UEFI so that's why I had to switch? I don't know though. Also, I reposted this post because I made one a few days ago with no answers, that is why I was mad. At least this one got answered.

   I have a Aleinware-51 R2 and I have changed the BIOS to Legacy and back to UEFI.  What I noticed was that the start-up Alienware logo had changed - I actually didn't put that together until I changed it again.  It boots rather slow but it boots and every thing is fine.  I think it was on some thing other than UEFI when I got it because it wasn't reporting the size of my hard drives.  So I changed it.  I notice that it still doesn't always report hard drive volume as the correct size in other settings. 

   I started looking here because I want to know how to optimize the settings on my BIOS.  I think they may be wrong or not optimal.  I know you can push a button to set default optimal settings but I don't want to do that.  I am running A11 (Now A12 June 11, 2017) but I don't know what the SMBIOS Version 3.0 is all about?  Does anyone know how to optimize the BIOS settings?  The Motherboard is Intel but Intel has little to do with the upgrade in BIOS.  I don't see an actual motherboard name but it does list vendor and manufacturer as Alienware with a number for Product and ePPID serial number possibly.

   Can any one help?

Zoeymae wrote:

   1. I have a Aleinware-51 R2 and I have changed the BIOS to Legacy and back to UEFI.

 

2. What I noticed was that the start-up Alienware logo had changed -

3. I know you can push a button to set default optimal settings but I don't want to do that.  

4. The Motherboard is Intel but Intel has little to do with the upgrade in BIOS.  I don't see an actual motherboard name but it does list vendor and manufacturer as Alienware with a number for Product and ePPID serial number possibly.

1. Not really a good idea to be switching back-and-forth. Pick one instead. In UEFI Mode, Windows has partial control of BIOS. 

2. Normal for some systems. My Lenovo does that. UEFI Mode usually boots faster.

3. Sometimes you must. Write settings down first or take phone pics.

4. It's a Dell motherboard. Made for them (and to their specs) by a company like Foxconn or MSI. 

Thanks

I really want to Optimize the Motherboard.  Settings, numbers, etc.  Can help? 

you should have created your own Thread. but it's okay now.

i have the same System and BIOS Version as you. there is not much to do.
Boot
Wait for F1 if Error = No Errors (thats how i have it)
Legacy Boot Option = Disabled
Secure Boot = Enabled
Install Secure Boot Keys (hit Enter, then click Yes)
1st Boot = Hard Disc Windows...
All Other Boot Devices = Disabled
F10 + Yes.

you're done.

if you have more Questions, go ahead and create your own Thread.

This isn't a BIOS discussion?  UEFI vs Legacy and what that actually means? BIOS Settings? 

Thanks Anyway

now you showed me huh?

the Thread is for Aurora R4 and it's an old Thread. now, everytime when someone replys, all the Others, who posted  before, will get a Notification / E-Mail. and what's the Subject? your Area 51 R2.

no problem anyway.

Of course,  I see now.  My Bad!

Thanks