Mikkel_1 :
Barty1884 :
Without knowing your motherboard, it's difficult to say.
Provided your board can accommodate 16GB (ie doesn't max at 4GB) & 2400MHz (ie the compatibility doesn't stop lower at say 1333MHz) you should be fine.
That being said, you'll likely be fine with 1600MHz or 1866MHz anyway. You won't see proportionate increases (in line with the price difference anyway) in regular use. Saving around $25-30USD
m4a79xtd evo is the name
Ok, that limits what you can do.
You can have a maximum of 16GB across the 4xSlots (4x4GB)
There's always a chance 2x8GB will work, but I would suspect it will not.
For 16GB, you'll need to buy a kit of 4x4GB and populate all slots.
For 8GB you have two options:
1. Try to find identical 2x2GB to match the ones you have installed (not recommended)
2. Buy a 2x4GB kit and install in the correct slots (I can't find an English manual* to confirm, but attempting to read the French one it looks like slots A1 & A2 for dual channel)
*ASUS Support website: http://www.asus.com/Motherboards/M4A79XTD_EVO/HelpDesk_Manual/