BootCamp 5.0 error on 13" MacBook Pro Mid-2010: "Installation Error. Boot Camp x64 is unsupported on this computer model"

Question

Installing Boot Camp 5.0.5033 (downloadable at http://support.apple.com/kb/DL1638) on Windows 8 x64 on 13” MacBook Pro Mid-2010 using BootCamp\setup.exe, I get the following message: “Installation Error. Boot Camp x64 is unsupported on this computer model”.
According to http://support.apple.com/kb/HT5634, Windows 8 x64 is not supported by Boot Camp 5 on 13” MacBook Pro Mid-2010 .
Previous version, Boot Camp 4.0, causes bluescreens on Windows 8 (https://discussions.apple.com/message/20131524#20131524).
Fortunately, it might be still possible to employ updated Boot Camp by launching “msiexec /i BootCamp.msi” from BootCamp\Drivers\Apple folder using administrative command prompt (http://technet.microsoft.com/en-us/library/cc947813%28v=WS.10%29.aspx).
However, new Boot Camp 5.0.5033 does not contain all the drivers for 13” MacBook Pro Mid-2010. E.g. driver for NVIDIA nForce System Management Controller (labeled Other devices/Coprocessor in Control Panel) and NVIDIA nForce PCI Systems Management (labeled Other devices/SM Bus Controller in Control Panel) must be obtained at Drivers\NVidia\NVidiaChipset64 in older Boot Camp 4.0 (downloadable at http://support.apple.com/kb/DL1634)
According to Microsoft (http://windows.microsoft.com/en-US/windows-8/system-requirements), the MacBook Pro config (Intel Core 2 Duo P8600 2.4GHz, 4GB RAM) exceeds Windows 8 x64 hardware requirements. Windows Experience Index for this laptop is approx. 5.1 (http://windows.microsoft.com/en-US/windows-8/what-windows-experience-index).
Does anybody know, is there any technical reason why Windows 8 x64 is not supported by Boot Camp 5 on 13” MBP Mid-2010?
Is there a specific hardware/firmware deficiency in this MacBook model, incompatible with Win8? Maybe NVIDIA refused to provide Win8-compatible drivers for its chipset components (GeForce 320M graphics card though is still supported by latest notebook drivers available at www.geforce.com)?

Answer 1

Thanks for the detailed explanation! If MacBook supports AHCI/SATA only in native “UEFI mode”, while reverting back to PATA/IDE in legacy “BIOS mode”, then it could make perfect sense to use UEFI to make sure that technology like Native Command Queuing (NCQ) is employed, as it may give noticeable performance improvements for certain operations: www.happysysadm.com/2012/12/intel-g530-nas-performance-part-3.html. I wonder how do you get Windows 8 x64 with EFI bootloader installed on MacBook?
Simply choosing EFI Boot (“Some EFI platforms support both UEFI and BIOS firmware. On some of those systems, it is not always clear if the default DVD boot option is an EFI or BIOS boot option. On these systems, using the EFI shell command may be required. If you do not specifically start Windows Setup by using the EFI boot entry, the default firmware boot entry for BIOS may be used. If Windows Setup starts in BIOS mode on a combined EFI/BIOS system, the ESP and MSR partitions are not created.”) from Win8 x64 DVD when installing on blank HDD would yield “The computer restarted unexpectedly or encountered an unexpected error. Windows installation cannot proceed" message. Also, if the hard drive was not in SATA mode during Windows installation, registry tweaking may be required before switching from PATA to SATA. Do you do registry tweaking and EFI bootloader configuration manually after a copy of Windows was installed in its dedicated partition in a regular way?