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

Mortandos Author

Level 1

4 points

Jun 24, 2015 9:14 AM in response to Loner T

Trying to understand the Boot Camp Assistant, now that through modifying the info.plist I can actually let the BCA create a bootable USB stick I am surprised that the operation fails. While copying the Windows files it eventually results in an error message and when I look at the stick then it's not wonder why. BCA formats the stick as FAT32 so when it's time to copy the Windows installation file it fails because of the file limitation. I have the original Windows 7 and Windows 8 DVD's, no downloaded copies, just as they come from Microsoft. How are other people doing that using the BCA? Shouldn't they run into the same problem?

Mortandos Author

Level 1

4 points

Jun 24, 2015 9:46 AM in response to Loner T

Here it is:

diskutil info disk2

Device Identifier: disk2

Device Node: /dev/disk2

Part of Whole: disk2

Device / Media Name: Kingston DataTraveler 2.0 Media

Volume Name: Not applicable (no file system)

Mounted: Not applicable (no file system)

File System: None

Content (IOContent): FDisk_partition_scheme

OS Can Be Installed: No

Media Type: Generic

Protocol: USB

SMART Status: Not Supported

Total Size: 15.6 GB (15610576896 Bytes) (exactly 30489408 512-Byte-Units)

Volume Free Space: Not applicable (no file system)

Device Block Size: 512 Bytes

Read-Only Media: No

Read-Only Volume: Not applicable (no file system)

Ejectable: Yes

Whole: Yes

Internal: No

OS 9 Drivers: No

Low Level Format: Not supported

Mortandos Author

Level 1

4 points

Jun 24, 2015 11:52 AM in response to Loner T

The other one is a TrekStor:

Device Identifier: disk10

Device Node: /dev/disk10

Part of Whole: disk10

Device / Media Name: USB Stick 2.0 ME Media

Volume Name: Not applicable (no file system)

Mounted: Not applicable (no file system)

File System: None

Content (IOContent): FDisk_partition_scheme

OS Can Be Installed: No

Media Type: Generic

Protocol: USB

SMART Status: Not Supported

Total Size: 8.0 GB (8019509248 Bytes) (exactly 15663104 512-Byte-Units)

Volume Free Space: Not applicable (no file system)

Device Block Size: 512 Bytes

Read-Only Media: No

Read-Only Volume: Not applicable (no file system)

Ejectable: Yes

Whole: Yes

Internal: No

OS 9 Drivers: No

Low Level Format: Not supported

I can pick up s San Disk from the Store but like I said - at this point I would prefer the Winclone partition upload if that's not too much too ask (doesn't depend on a couple more days).

Mortandos Author

Level 1

4 points

Jun 24, 2015 1:43 PM in response to Loner T

No, I tried all 3 ones, same result:

Your bootable USB drive could not be created.
An error occurred while copying the Windows installation files.

How is that supposed to work theoretically? Windows 7 and 8 both have an installation file that's too big for FAT32.

Loner T

Level 9

59,536 points

Jun 24, 2015 3:52 PM in response to Mortandos

Mortandos wrote:

How is that supposed to work theoretically? Windows 7 and 8 both have an installation file that's too big for FAT32.

This is not true. If you look at https://technet.microsoft.com/en-us/library/cc938937.aspx?f=255&MSPPError=-21472 17396 the largest file size on FAT32 is 2^32 -1 bytes which is 4294967296 = 4 GB - 1 byte. My example shows a 3.6G file. This is not a FAT32 issue.

Can you check Applications -> Utilities -> Console logs for any errors related to the USB?

Mortandos Author

Level 1

4 points

Jun 24, 2015 5:06 PM in response to Loner T

My Windows 7 install.wim file is more than 4 GB (probably because it's Windows 7 Ultimate, I borrowed it from work). My Windows 8 installation file is 4.51 GB. I don't have access to any other versions and I don't want to mess around with illegal copies so I cannot test that any further.

Loner T

Level 9

59,536 points

Jun 24, 2015 6:36 PM in response to Mortandos

You can ask your Windows support team to recreate the .wim file for just the version of windows you want. Currently, you have a .wim file which covers several variants of windows which is causing the size to be over 4GB.

Mortandos Author

Level 1

4 points

Jun 24, 2015 6:43 PM in response to Loner T

Good point however that doesn't mean that this will solve my problem that my iMac will actually boot from the stick (it should have booted from the version I created with Rufus). Is that creating a Winclone BC file on your end still on the table?

Loner T

Level 9

59,536 points

Jun 24, 2015 7:24 PM in response to Mortandos

Yes. It will take a couple of days to find a machine and installer to create a Winclone image. If you can, please post a dropbox link which has your installation media. I can use it and create a Winclone backup for you much quicker and it will save you time. If your installation media is a Volume License, then I do not recommend you putting it in dropbox.

Jul 12, 2015 3:10 AM in response to Mortandos

Mortandos,

I have the exact same problem that you have ( Mid-2011 iMac ith dead superdrive, can't get sound and more than 2.x Gb mem on Windows 7 ).

I am in the process of following all the ideas here, so if you finally found something that works, let us know (currently I am copying a sysprepeed partition from a VirtualBox install directly into the boot camp partition and using ReFind to boot it, but I only get the black screen with blinking cursor...)`

Loner T

Level 9

59,536 points

Jul 19, 2015 5:37 AM in response to Mortandos

Consider the following

1. Go to the nearest Apple Store, if possible, talk to the Manager, and get a MBP in the store (even if you have to buy it). Take your installer media, and a USB2 flash drive. Install Windows on this brand new Mac.

2. Run Winclone (or similar) with Sysprep.

3. Copy this 'generalized' Windows image to your 2011 Mac (or a portable disk), which is hardware agnostic and restore it on your Mac with a broken optical drive.

4. Return the new Mac and ask the store to ensure they wipe it, which is within the 14-day Apple Return policy in the US or applicable local policy.

5. If you run into any issues, please post back here.

Loner T

Level 9

59,536 points

May 4, 2015 2:25 PM in response to Mortandos

Are you using an account on Windows which has Administrative Rights?

Mortandos Author

Level 1

4 points

May 4, 2015 2:40 PM in response to Loner T

Yes, there is only one account and I checked, it shows my name, email address and then the word ADMINISTRATOR.

Loner T

Level 9

59,536 points

May 4, 2015 5:43 PM in response to Mortandos

Is this a new installation of Windows?

Loner T

Level 9

59,536 points

May 4, 2015 7:43 PM in response to Mortandos

1. What is the year/model of your iMac?

2. Was Windows installed using EFI Boot?

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