Hackintosh and 4GIG RAM

[macwanabe]

Hi all

When I install 4GIG RAM my system hangs when more than 3.2 GIG is used, have tried different kernels etc. Not making a difference. Have searched and don't get a straight answer. How can we fix this.

System Specs
Gigabyte P965 DS3 Motherboard
Intel Q6600 Quad core CPU clocked 3.0Ghz
SAMSUNG DDR2 800 RAM 4 x 1 GIG

Thanks for some info.

[BaZola]

I second this one. I have the same problem and I am using the same motherboard. Mine likes to Kernel Panic about 500 megs before the total of 4gigs is up.

when I pull a stick of ram out and only use one 2gig stick, it works fine.

hoping someone here has the solution.

[g3monster]

You have hit the 4gb limit...after 3gb BIOS devices cache in the range of 3-4GB so you can only use the RAM upto 3.2GB because that the maximum accessible ram in 32bit...OS X is seeing all 4GB of ram but when the RAM usage gets past 3.2GB you will hit problems because that ram is reserved for BIOS caching. using a 64 capable kernel and making sure 64 bit mode is enabled should fix the problem but if it doesnt youll have to w8 for Leopard which is 100% 64bit capable.

[macwanabe]

Thanks for the feedback using the following kernel, as far as I know this is 64 bit capable.

8.9.1 Darwin Kernel Version 8.9.1: Sun Jul 8 18:18:57 UZT 2007; made by ToH:xnu-792.18.15/BUILD/obj/RELEASE_I386 i386 i386

How do I check to see if 64 bit is enabled.

Thanks

[g3monster]

Thanks for the feedback using the following kernel, as far as I know this is 64 bit capable.

8.9.1 Darwin Kernel Version 8.9.1: Sun Jul 8 18:18:57 UZT 2007; made by ToH:xnu-792.18.15/BUILD/obj/RELEASE_I386 i386 i386

How do I check to see if 64 bit is enabled.

Thanks

The fact that the kernel release has i386 specifically in its title doesnt bring confidence. I have a feeling that the kernel is running in 32 bit mode (i386) where as 64 bit mode should be reported as either x64/Ix64 or IA64. (but could be completely wrong here)

You could try a 10.4.10 update + kernel and see if that fixes your problem otherwise you could give me a gig of ur RAM:p :D

[macwanabe]

Ok good news, I have been able to get it to work.

Updated to 10.4.10 with the patched 10.4.10 kernel, this kernel it seems are able to utilize all of the ram no more kernel panics when more than 3.2 GIG is used.

[g3monster]

good to hear.

[BaZola]

Ok..updated to 10.4.10 (8R2218) with 8.10.1 Kernel....and I still get a kernel panic and computer must be restarted.

Can anyone please advize?

I would love to solve this problem. my hack is working perfectly except for this one lame event.

[BaZola]

I think I found it............

In an superb explanation regarding the 3 GB memory limitation in the MacBook Pro, the always excellent MacFixIt notes that:

The MacBook Pro Core 2 Duo presumably uses Intel's 945PM chipset, which can physically handle 4 GB of DDR2 RAM. However, a number of items must be stored in physical RAM space, and when RAM reaches 4 GB, there is some overlap.

In other words, in a 3 GB RAM configuration, there is no overlap with the memory ranges required for certain system functions. Between 3 GB and 4 GB, however, system memory attempts to occupy space that is already assigned to these functions. For instance, the PCI Express RAM allocation occurs at somewhere around 3.5 GB of RAM and requires 256 MB of RAM. Thus, the virtual space between 3.5 GB of RAM and 3.75 GB of RAM is occupied by PCI Express data. So in a system with 3 GB of RAM, nothing is being wasted because the memory space required by PCI Express is still between 3.5 and 3.75 GB, and the installed system RAM does not violate this space.

The net result is that at least 3 GB of RAM should be fully accessible, while when 4 GB of RAM installed, ~700 MB of of the RAM is overlapping critical system functions, making it non-addressable by the system.

Ultimately, RAM in excess of 3 GB cannot be used due to the possibility of memory "overlap".

For highly technical details, one also may choose to refer to the Intel datasheet for the Mobile Intel 945 Express chipset. Chapter 9, starting on page 317, and in particular pages 324-325 may be of interest.

[nargot]

using 8.10.1 kernel on the mobos 965-DS3/DQ6 and P35-DS3P 4 gb ram will be utilised without kernel panics. Problems you will encounter are random kernel panics.

Apparent solution (currently testing, when i'm 5 days uptime i'll be happier) is to disable the JMicron controller in BIOS. after that you sould have full system stability and 4gb+ ram.

[nargot]

I think I found it............

In an superb explanation regarding the 3 GB memory limitation in the MacBook Pro, the always excellent MacFixIt notes that:

The MacBook Pro Core 2 Duo presumably uses Intel's 945PM chipset, which can physically handle 4 GB of DDR2 RAM. However, a number of items must be stored in physical RAM space, and when RAM reaches 4 GB, there is some overlap.

In other words, in a 3 GB RAM configuration, there is no overlap with the memory ranges required for certain system functions. Between 3 GB and 4 GB, however, system memory attempts to occupy space that is already assigned to these functions. For instance, the PCI Express RAM allocation occurs at somewhere around 3.5 GB of RAM and requires 256 MB of RAM. Thus, the virtual space between 3.5 GB of RAM and 3.75 GB of RAM is occupied by PCI Express data. So in a system with 3 GB of RAM, nothing is being wasted because the memory space required by PCI Express is still between 3.5 and 3.75 GB, and the installed system RAM does not violate this space.

The net result is that at least 3 GB of RAM should be fully accessible, while when 4 GB of RAM installed, ~700 MB of of the RAM is overlapping critical system functions, making it non-addressable by the system.

Ultimately, RAM in excess of 3 GB cannot be used due to the possibility of memory "overlap".

For highly technical details, one also may choose to refer to the Intel datasheet for the Mobile Intel 945 Express chipset. Chapter 9, starting on page 317, and in particular pages 324-325 may be of interest.

All good for 945 chipsets its a known limitation. However, for the case of these 965+ chipsets which can take 8gb ram no problems, the original problem was probably a problem with both the kernel and JMicron controller.

[ekwipt]

+1 on disabling the JMicron controller.

Another thing is, don't read the support list for the 965 motherboards that say they can handle 4 gigs of ram, they can't (or can't do it weel), stick to either 3 gigs or get a P35

[BaZola]

My Mobos (P35-DS3P) just crashed for the last time and now I fixed my last issue with my OSX thanks to your clue nargot. Thank you!! Disabling the JMicron doesn't work for me as I cannot get my CD RW to run on sata (yes I have the right converter), but what I was able to do is set the Jmicron to IDE ( not ahci) and plug my Sata drive into the top orange port and now my system doesn't crash at the ram limit.

My cd rw isn't reading as fast (a bit sticky) but at least I am able to use 4 gigs of ram and I am very happy about that.

I think this is really MB related.