Level 1

4 points

Why can I only use 2.48 GB RAM in Boot Camp (Win 8.1 Pro, 64-bit)?

Hello, I am fairly new to the iMac and I have to use some programs in Windows that are not available for Mac so I set up Boot Camp and installed Windows 8.1.

My iMac is a I7-2600 CPU @ 3.4GHz with 16 GB RAM, system type-bit. Under system in Windows it shows Installed memory (RAM) 16 GB (2.48 GB usable).

I read about this problem and most answers are related to people using 32-bit. So what is wrong in my case, where is the problem?

Thank you in advance for help and suggestions.

iMac, OS X Yosemite (10.10.3)

Posted on May 3, 2015 11:52 AM

Top-ranking reply

Loner T

Level 9

59,536 points

Posted on May 4, 2015 8:04 PM

Your 2011 iMac is a preUEFI Mac (all Macs prior to Late 2013 models are). The preUEFI Macs support varying degrees of EFI boot capability, but do not fully comply with UEFI specifications. This causes various BC drivers to work, not work, or partially work, depending the year of the Mac and the OS used.

There are two methods that have been "successful" in working around broken Optical drives (apart from replacing it).

1. http://forums.macrumors.com/showthread.php?p=20584499#post20584499

2. Bootcamp without Optical disc drive

My recommendation is to remove Windows using BC Assistant (only, nothing else), and then try either of these two methods. You want a legacy BIOS installation (aka Hybrid MBR method). The CSM-BIOS layer correctly exposes hardware for preUEFI machines. It will also address your memory visibility issue.

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195 replies

Loner T

Level 9

59,536 points

Jun 22, 2015 1:16 PM in response to Mortandos

Yes. Remember, this also requires running SysPrep which has a limited number of attempts due to Windows licensing restrictions.

Mortandos Author

Level 1

4 points

Jun 22, 2015 3:42 PM in response to Loner T

It seems that this is my last option. Any links / documentation that you know of (that are reliable)? Did it work for you?

Loner T

Level 9

59,536 points

Jun 22, 2015 5:41 PM in response to Mortandos

The Winclone is well written and self-contained. If you buy the product, you will also get Technical Support. I have not run into any issues so far.

Loner T

Level 9

59,536 points

Jun 22, 2015 6:59 PM in response to Mortandos

You need to use the --deep qualifier. See man codesign for details.

Mortandos Author

Level 1

4 points

Jun 22, 2015 7:09 PM in response to Loner T

unfortunately I don't know what you're talking about. Is that regarding the terminal command? Can you please post the correct command?

And regarding the question on the Windows laptop?!

Mortandos Author

Level 1

4 points

Jun 23, 2015 1:54 PM in response to Loner T

1) this still results in "Boot Camp Assistant quit unexpectedly." Any idea why?

I'll look in to #2 and #3 later, thank you.

Loner T

Level 9

59,536 points

Jun 23, 2015 3:08 PM in response to Mortandos

Please try

sudo codesign --deep --verbose -fs - /Applications/Utilities/Boot\ Camp\ Assistant.app

Loner T

Level 9

59,536 points

Jun 23, 2015 3:36 PM in response to Mortandos

Can you post the output of the codesign command?

Unless you have a license to install Windows on an external drive, it will not work.

Loner T

Level 9

59,536 points

Jun 23, 2015 5:02 PM in response to Mortandos

I do not have a Mac on which I can install a fresh copy. Can you wait till tomorrow, so I can get a Winclone on a spare Mac?

Loner T

Level 9

59,536 points

Jun 24, 2015 9:56 AM in response to Mortandos

I have had issues in the past with Kingston flash drives. Do you a SanDisk USB flash drive which 8GB or larger?

Loner T

Level 9

59,536 points

Jun 24, 2015 12:16 PM in response to Mortandos

Are you able to create the BC USB on this one?

Mortandos Author

Level 1

4 points

Jun 25, 2015 4:58 PM in response to Loner T

I didn't know that you can't send any PM here, I don't feel comfortable to post the link in a public forum.

Mortandos Author

Level 1

4 points

Jun 29, 2015 10:29 AM in response to Loner T

Any news in the meantime?

Loner T

Level 9

59,536 points

Jul 12, 2015 8:31 AM in response to Mortandos

Mortandos wrote:

Any news in the meantime?

I am unable to find the appropriate hardware to create a Winclone for you. I am still looking.

Loner T

Level 9

59,536 points

Jul 19, 2015 10:10 AM in response to Loner T

@Mortandos

l o n e r t m a c at g m a i l d o t

If you need it.

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Why can I only use 2.48 GB RAM in Boot Camp (Win 8.1 Pro, 64-bit)?