New machines ONLY boot UEFI they no longer have MBR LEGACY DOS compatable bios. (No dos floppy Boot Nor WIN9X USB Flash Booting, NO EL TORITO DOS CD BOOTING) This is to prevent them from using MBR and GRUB and Linux. It also means only GPT partitions so SYSLINUX GRUB DOS MBR Boot sectors won't ever work(It also broke cloning software from many vendors)

The only advantage of UEFI is breaking the 2TB MBR partition Limit.

All of the rest is advantage for making computers that will boot WINDOWS 8 only.

CLASS 3 UEFI Bios has NO CSM (LEGACY MODE) and therefore will NEVER BOOT ANY OS Other than Windows 8 or company that has paid microsoft for a WINDOWS 8 boot Certificate.

@ SpeedStep,

Thanks. Is there a utility that we can run that identifies UEFI Class Level?

Or, do we determine it ourselves, based on ...

- The presence of CSM (Legacy Mode) Option in BIOS?

- If a new Windows-8 machine is advertised to also support Win-7 and/or Linux ... is that an definitive indication of Class 0-2 (ie NOT Class-3)?

- Manufacturer supplied System Specification documentation (not that I'm ever seen it mentioned).

Seems like a vital piece to know pre-sales before ordering machines.

The Indication of Class 0 or Class 1 is Basic Bios INT13 with MBR.

These machines will boot DOS and Syslinux from FAT or FAT32 partitions as well as El Torito DOS based Bootable CD's.

Class 2.3 has Secure boot with CSM aka Legacy mode. There is no more DOS MBR only GPT partitions. USB Booting can only be done via GPT/NTFS via the Microsoft USB Tool. No more Floppy boot options exist.

Class 3.0 is Windows 8 only forever there is no legacy mode and no old cards with non Secure boot bios or storage controllers or anything else. Drivers that are not WHQL with certificate will not load nor will BIOS that is not WHQL microsoft Certified.

Thanks Tesla1856!  That was a very helpful reply, and pretty much says it all.  I am on the x58 chipset, so this is just something I missed out on.  I'll leave things as-is because it all runs great but this was just curiosity.  Thanks again for giving me a precise answer and some great explanation.

Thanks Speedstep!  These posts explain a lot.  I've read bits & pieces about the BIOS and UEFI over the years, but you've provided some details I didn't know about.

Much appreciated.

Can I infer from your comments that there is no way to get my 64-bit Alienware Area 51 to recognize the full capacity of a 4TB internal hard drive? I have Windows 7 Enterprise OS.

Thanks!

Can I infer from your comments that there is no way to get my 64-bit Alienware Area 51 to recognize the full capacity of a 4TB internal hard drive? I have Windows 7 Enterprise OS.

It should work, you just can't boot from it. Make it a "data drive" formatted as GPT.

http://www.hgst.com/tech/techlib.nsf/techdocs/869E4925CC72E233862577E100235119/$file/Deskstar_3TB_FAQ_finalwebv2.pdf

http://msdn.microsoft.com/en-us/library/windows/hardware/dn653580(v=vs.85).aspx

New machines ONLY boot UEFI they no longer have MBR LEGACY DOS compatable bios. (No dos floppy Boot Nor WIN9X USB Flash Booting, NO EL TORITO DOS CD BOOTING) This is to prevent them from using MBR and GRUB and Linux. It also means only GPT partitions so SYSLINUX GRUB DOS MBR Boot sectors won't ever work(It also broke cloning software from many vendors)

This is not correct. Linux and GRUB can boot with UEFI just fine, and MBR is still a part of the UEFI specification. Windows requires GPT in UEFI mode, but that's a limitation of Windows, not a requirement of the UEFI specification.

The only advantage of UEFI is breaking the 2TB MBR partition Limit.

Incorrect. There are plenty of advantages to UEFI. UEFI isn't even required for GPT, systems other than Windows can boot from GPT partitions with legacy BIOS just fine.

All of the rest is advantage for making computers that will boot WINDOWS 8 only.   CLASS 3 UEFI Bios has NO CSM (LEGACY MODE) and therefore will NEVER BOOT ANY OS Other than Windows 8 or company that has paid microsoft for a WINDOWS 8 boot Certificate.

Now you're confusing the lack of CSM with Secure Boot, an optional feature of UEFI.

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