Re: Crash and burn
The RAM slots will be colour coded – if you have 2 sticks you need to use slot 1 and slot 3 – they will be the same colour.
IF you new 4gb is not EXACTLY the same spec/speed as the 8gb, I would stick with using only the 8GB – otherwise if you use all three they will all run at the speed of the slowest stick.
I also only use Asus boards and usually the boot menu key is F8 – alternatively try F5