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Why can't I upgrade to Mavericks when running OSX Lion ?

I have a mac Pro Desktop OSX Lion 2x 2.66 GHz Dual Core Intel Xeon and 16 GB 667 MHz DDR2 FB-DIMM running right now and I got a free software update to install OSX Mavericks and when I clicked on it to install it and it read that it couldnt be installed ? how can I get this free upgrade and install it on my MacPro? anybody come across this issue? please help. thanks

Mac Pro, Mac OS X (10.7.5)

Posted on Apr 25, 2014 12:19 PM

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Posted on Apr 25, 2014 12:43 PM

Yours and mine are 1,1 models, the infamous EFI-32 and does not support 64-bit drivers and kernel mode. Snow Leopard+ are 64-bit mode only. The only way is non-Apple installer and boot loader tools.


so yes well known, it was two years ago when 10.8 came out.

5 replies

Apr 25, 2014 7:53 PM in response to the amigo

There is a complex set of hacks that can load the 64-bit firmware into Main RAM and execute it from there. It takes extra RAM, and you need to be a developer (or think like one) because it takes a bit of fiddling to get working, and especially to keep it working if you run into a problem.


This is unsupported software, and Apple will not help you with it if you get into a jam.

Why can't I upgrade to Mavericks when running OSX Lion ?

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