Quick Question: ASUS P5K PREMIUM/WIFI-AP (4GB Ram)

Have you gone to their website? I not picking on you but you should really grab all the low hanging fruit before asking questions.

This forum is better for getting opinions as opposed to facts.

I have a P5K-E Deluxe Wifi AP and its pretty mugh the same board minus a few extras Asus puts in.

In DDRs 1066 mode you can only populateeither the yellow rows or black rows dual channel. So you cannot put in 4 1GB sticks but you can put in 2 2GB(4GB total) sticks and it will run Dual channel 1066. They have a "Qualified vendors list" but thats just who they have tested.

As for the limitation reason, according to Asus it is the chipset P35 but I am not too sure about that. Intel designed this chipset(bearlake) for support of Conroe and Penryn. Penryn is going to have a base FSB of 1333.

The P35 and the X38 are basically the same chipset but the X38 introduces a few new items such as a speed up for DDR3, PCIe 2.0 and support for 2 true 16x PCIe lanes for better PCIe 1.0 dual cards.

So I think its a limitation of the board really.

As for you question about having 4x1GB sticks of DDR2800 yes it can support it you just wont have the 1066 FSB. Plus make sure you are using a 64-bit OS for sull support and use of the full 4GB.