This article was born due to my successfull hardware upgrade from ASUS P5K-SE to GIGABYTE GA-EP45-DS3L.
After that I decided to write mini how-to that can help others with their feature upgrades for their Mac-ready hardware configurations.

So. If You are planning to live with Mac OS - nice practice is working with USB2SATA adapter as repair solution when drivers failed to load Your system after software update or hardware upgrade.
Such devices are cheap and I see no problems for getting it.

Before upgrading

If Your OS X working well at old hardware - You have to backup all of Your System based data for making possible to start up old OS on old hardware if something goes wrong with a new hardware configuration.

Here is a list of important data for a backup(best way is to do these steps in Terminal with super user (sudo -s) ) and prepare.

• Create backup directory (Terminal commands)

mkdir /before.upgrade

• backup /Library/Preferences/SystemConfiguration/com.apple.Boot.plist

cp /Library/Preferences/SystemConfiguration/com.apple.Boot.plist /before.upgrade/
I`d like to mention that You have to remove from com.apple.Boot.plist all Efi-based strings(for Your sound or video card or any)
Example from one my install
Before

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Graphics Mode</key>
<string>1280x800x32</string>
<key>Kernel</key>
<string>mach_kernel</string>
<key>Kernel Flags</key>
<string></string>
<key>Timeout</key>
<string>5</string>
<key>device-properties</key>
<string>6d0000000100000001000000610000000200000002010c00d041030a
000000000101060001027fff0400100000006d006f00640065006c0000000b
000000474d4120393530200000004100410050004c002c00480061007300
500061006e0065006c0000000800000001000000</string>
</dict>
</plist>

After

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Graphics Mode</key>
<string>1280x800x32</string>
<key>Kernel</key>
<string>mach_kernel</string>
<key>Kernel Flags</key>
<string></string>
<key>Timeout</key>
<string>5</string>
</dict>
</plist>
• /System/Library/Extensions

Backing up Extensions to backup folder
cp -Rv /System/Library/Extensions /before.upgrade/

• Removing All Injectors (Video, Audio)

rm -rf /System/Library/Extensions/*injec* && rm -rf /System/Library/Extensions/*enable*

• Move all Extensions outside of /Extra/Extensions folder if You are using EFIv9 bootloader

mkdir /before.upgrade/Extra && mv -v /Extra/Extensions /before.upgrade/Extra/

• Move any DSDT patches into backup folder

mv /DSDT.aml /before.upgrade/

• Good practice is to install new SATA controller drivers before hardware upgrade, but is not necessary If You have USB2HDD adapter

After that You can to upgrade Your hardware (motherboard, CPU, HDD controllers).

After upgrading

New hardware config should boot if Your Extensions compatible with a new HDD controller - if not - You always can boot via USB2HDD adapter with system disk installed.

First boot will be more successfull if You start it with
-v -f
boot keys (verbose booting and force reloading Extensions)

After booting You have to install all Your drivers for a new hardware and reconnect HDD(if needed) onto onboard HDD controller.

Can`t boot at new hardware

If Your new hardware is very unusual and can`t boot with a system disk neither via USB2HDD adapters - You always can make some repair steps described at Universal How-to MacOS installation.
You can boot Your upgraded system with installation DVD and make repair steps in Terminal program, provided there.

Goog luck.