''Look over the guides and notes or the teardown for''' for EMC 226, 2308 or 237''' how this machine is put tighter overall '''they are similar'''.''
Often AHT will not catch a problem with just one run if it's an overheat issue. You may need to run it 2 or 3x in succession.
''When was the last time this machine booted without the wait?'' Did you add apps, peripherals or change OS before the WSOD?
'''Check your free space '''on the HD. If you don't have 12GB or ~20% of the total that may be part of your boot problems.
White screen boot sometimes is a corrupt system folder.''' Try safe (shift) booting''' (faster?) and then''' creating a new master user and setting (or choosing that) as a log in''' may solve corrupt font/file issues. If not you may have to''' backup and wipe the drive then reinstall and update the OS.'''
You don't mention '''what OS you're running'''. ''If you've upgraded it from the original that may have a part in the slow down… or an attached peripheral.''
'''Try booting with no peripherals''' attached. (Faster?)
'''Try turning off Bluetooth''' and using a USB keyboard/mouse (any kind will work - doesn't have to be Apple) Faster?
''If this answer is acceptable '''please remember to return and mark it accepted'''.''